To install APEX (Oracle Application Express) on Oracle 10g. Follow those step-by-step to install it: :

1. Download the latest version from APEX website

2. Unzip the archive in a convenient location on your hard-disk

3. Start a SQL*Plus from that location

C:\APEX\>  sqlplus  /  as  sysdba

Install APEX:

@apexins SYSAUX SYSAUX TEMP /i/

Change admin password:

@apxchpwd

Set images path (APEX_HOME is the folder where you unziped the archive):

@APEX_HOME/apex/apxldimg.sql APEX_HOME

Run the following script where “password” is the admin password set 2 steps before:

@APEX_HOME/apex/apxxepwd.sql password

First, connect to Oracle via SQL*Plus:

$ sqlplus / as sysdba

SQL> show user

SQL> select  username, account_status, expiry_date  from  dba_users;

SQL> alter user scott account unlock;

SQL> grant connect to username identified by password;

SQL> ----- Change/Reset user's password to abc12345

SQL> alter user username identified by abc12345;

/u[0-9]

/*/home/*

/*/app/*

/*/app/appmgrr

/*/app/oracle/product

/*/app/oracle/product/10.2.0

/*/app/oracle/admin/sab

/*/app/oracle/admin/sab/arch/*

/*/oradata

/*/oradata/sab/*

/*/oradata/sab/*.log

Before we can create an Oracle user account, we need the CREATE USER privileges. SYSTEM can grant the CREATE USER privilege to an user or rule.

GRANT CREATE USER TO admin_user;

SQL*Plus example to create user:

CREATE USER john IDENTIFIED BY p@$$word;

CREATE USER john IDENTIFIED BY EXTERNALLY;

To uninstall Oracle products. The two methods listed below should only be used as a last resort and will remove all Oracle software allowing a reinstall.

* Windows platforms
* UNIX platforms

Windows:
In the past I’ve had many problems uninstalling all Oracle products from Windows systems. Here’s my last resort method:

* Uninstall all Oracle components using the Oracle Universal Installer (OUI).
* Run regedit.exe and delete the HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE key. This contains registry entires for all Oracle products.
* Delete any references to Oracle services left behind in the following part of the registry:
  Click “Start->Run->Regedit32″
  HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Ora*
  It should be pretty obvious which ones relate to Oracle.
* Reboot your machine.
* Delete the “C:\Oracle” directory, or whatever directory is your ORACLE_BASE.
* Delete the “C:\Program Files\Oracle” directory.
* Empty the contents of your “c:\temp” directory.
* Empty your recycle bin.

At this point your machine will be as clean of Oracle components as it can be without a complete OS reinstall.

Remember, manually editing your registry can be very destructive and force an OS reinstall so only do it as a last resort.

UNIX:
Uninstalling all products from UNIX is a lot more consistent. If you do need to resort to a manual uninstall you should do something like:

* Uninstall all Oracle components using the Oracle Universal Installer (OUI).
* Stop any outstanding processes using the appropriate utilities:
  # oemctl stop oms user/password
  # agentctl stop
  # lsnrctl stop
  # emctl stop dbconsole
  Alternatively you can kill them using the kill -9 pid command as the root user.
* Delete the files and directories below the $ORACLE_HOME:
  # cd $ORACLE_HOME
  # rm -Rf *
* With the exception of the product directory, delete directories below the $ORACLE_BASE.
  # cd $ORACLE_BASE
  # rm -Rf admin doc jre o*
* Delete the /etc/oratab file. If using 9iAS delete the /etc/emtab file also.
  # rm /etc/oratab /etc/emtab
* Delete the /usr/local/bin/ora* files
  # rm /usr/local/bin/ora*

List of additional steps to do for cleaning the system completely after uninstall using universal installer.

Usually, we use Oracle Universal Installer (OUI) to deinstall oracle on Windows platforms.

C:\oracle\product\10.2.0\db_2\oui\bin\setup.exe

But, for you can follow those steps to uninstall/remove Oracle from your Windows platforms.

1. Stop any Oracle services that have been left running.
Click “Start->Settings->Control Panel->Services”

Look for any services with names starting with “Oracle” and stop them.

2. Run regedit and delete the following keys (some may have slightly different names in your registry):
HKEY_CURRENT_USER\SOFTWARE\ORACLE
HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet Services\EventLog\Application\Oracle.oracle
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet Services\OracleDBConsole
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet Services\Oracle10g_home
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet Services\OraclService
Note that the services control panel will still show the old services until you reboot.

3. Delete the Oracle home directory
C:\Oracle

4. Delete the Oracle Program Files directory:
C:\Program Files\Oracle

5. Delete the Oracle Start Menu shortcuts directory:
C:\Documents and Settings\All Users\Start Menu\Programs\Oracle*

Where * indicates the name of your install. Look for and remove all Oracle directories from that location.

6. Remove Oracle refereces from the path. To edit your path go to:
Start->Settings->Control Panel->System->Advanced->Environment Variables

Edit both of the environment variables user PATH and system PATH. Remove any Oracle references in them.

7. Remove Oracle.DataAccess and any Polic.Oracle files from the GAC which is at:
C:\Windows\assembws\ac

For experienced DBA’s, the manual uninstall is the preferred method of uninstalling Oracle

Step 1:  Nuke all Oracle processes.  The uninstall requires stopping all Oracle instances, listeners and daemon processes that are associated with the release:

$ORACLE_HOME/bin/shutdown abort
$ORACLE_HOME/bin/emctl stop dbconsole
$ORACLE_HOME/bin/lsnrctl stop
$ORACLE_HOME/bin/isqlplusctl stop

Step 2:  Take a full backup of $ORACLE_HOME.  In UNIX/Linux you can make a backup copy in case you need anything later:

root> tar -xvf $ORACLE_HOME > /dev/rmt0/bkup

Step 3:  Remove $ORACLE_HOME and all subdirectories.  You can use the DBCA uninstaller function if you are on 10g or beyond.  In UNIX/Linux you can remove the software footprint as follows:

root> cd $ORACLE_HOME

root> rm -RF *

Step 4: Remove entries in shared parm files.  The database may participate in server-side parameter files and you want to complete the uninstallation process by removing references to the database in these locations specified by the “dest” parameters in the init.ora file (e.g. log_archive_dest_n):

• tnsnames.ora
• protocol.ora
• listener.ora
• oratab (/etc or /var/opt/oracle)

Assisted Oracle uninstall

For beginners and those who are unfamiliar with the components of Oracle, the Oracle DBCA has assisted uninstall procedures:

Step 1:  Nuke all Oracle processes.  The uninstall requires stopping all Oracle instances, listeners and daemon processes that are associated with the release:

$ORACLE_HOME/bin/shutdown abort
$ORACLE_HOME/bin/emctl stop dbconsole
$ORACLE_HOME/bin/lsnrctl stop
$ORACLE_HOME/bin/isqlplusctl stop

Step 2:  Start the Database Creation Assistant (DBCA) and choose the remove database option

Step 3:  Use the assisted deinstall wizard.  Execute the Oracle Universal Installer (OUI)

$ORACLE_HOME/oui/bin/runInstaller

Step 4. In the OUI Welcome window, click the “Deinstall Products” button.

Step 5. In the OUI software Inventory screen, select the Oracle home and the products that you want to remove, cross your fingers and mash the “Remove” button.

Oracle’s installation utility has a nasty habit of leaving a lot of items behind.  I wrote this up to document what I’ve found you need to do to uninstall Oracle 10g manually.  This is specific to 10g and Windows XP.  Removing 9i is very similar if I remember right, but who’s using 9i anymore?

The first thing you should do, is go ahead and run the installation tool to do an uninstall.  It probably will leave some things behind, but it’s worth running.  Then go through this list and remove anything it missed.  This list is detailed enough though, that I believe even if you did not run the uninstallation tool, this would fully uninstall Oracle.

The most commonly missed item is to make sure you remove everything from the GAC because the uninstaller doesn’t appear to.  I get to that later, but if you wanted to know the largest source of uninstallation problems, it’s libraries remaining in the GAC.

After running the supplied Oracle uninstallation utility (which may or may not do some or all of the following):

# Stop any Oracle services that have been left running.
Start->Settings->Control Panel->Services
Look for any services with names starting with ‘Oracle’ and stop them.

# Run regedit and delete the following keys (some may have slightly different names in your registry):
HKEY_CURRENT_USER\SOFTWARE\ORACLE
HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Application\Oracle.oracle
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\OracleDBConsole
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Oracle10g_home
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\OraclService

Note that the services control panel will still show the old services until you reboot.

# Delete the Oracle home directory
C:\Oracle

# Delete the Oracle Program Files directory:
C:\Program Files\Oracle

# Delete the Oracle Start Menu shortcuts directory:
C:\Documents and Settings\All Users\Start Menu\Programs\Oracle*
Where * indicates the name of your install.  Look for and remove all Oracle directories from that location.

# Remove Oracle refereces from the path.  To edit your path go to:
Start->Settings->Control Panel->System->Advanced->Environment Variables
Edit both of the environment variables user PATH and system PATH.  Remove any Oracle references in them.

# Remove Oracle.DataAccess and any Polic.Oracle files from the GAC which is at:
C:\Windows\assembly\

There, now your system is Oracle free.  If you are installing a new instance of Oracle (and not just an additional DB) I recommend you do this before any new Oracle installation.
Note: I used several other websites and searches as references when developing these steps, but I was unable to find any steps that covered all of the items for Oracle 10g so I assembled them here.

http://www.ibm.com/support/docview.wss?rs=71&uid=swg21255352

http://www-1.ibm.com/support/docview.wss?rs=71&uid=swg21256235

http://www-01.ibm.com/support/docview.wss?rs=71&uid=swg27007053

Fixes by version for DB2 for Linux, UNIX and Windows

http://www-01.ibm.com/support/docview.wss?rs=71&uid=swg27007053

First, you want to stop the mysql daemon.
# /etc/init.d/mysql stop
Second, issue a command to allow you to change the mysql root password by skipping the tables that grant permissions.
# mysqld --skip-grant-tables
Next, using mysqladmin you can now change the root password
# mysqladmin -u root password 'newpasswd'
That’s it! Now you can start the mysql daemon again.
# /etc/init.d/mysql start