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:
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.
If some DLLs can’t be deleted, try renaming them, the after a reboot delete them.
( OR )
Oracle11g introduce new utility “deinstall” to uninstall/deinstall oracle database with configuration files.
run deinstall.bat file $ORACLE_HOME/deinstall/deinstall.bat
and give the prompt details then system will remove all the related files/services/folder.
if oci.dll not delete during deinstall process then restart system and delete manually.
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
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
