Cause
The Oracle system identifier (SID) given was already in use.
Action
Specify a unique Oracle system identifier (SID).
What is it cause? How could I fix it?
Cause
The Oracle system identifier (SID) given was already in use.
Action
Specify a unique Oracle system identifier (SID).
What is it cause? How could I fix it?
You can find here How to uninstall / completely remove Oracle 11g (client)?
Calling additional attention to some great comments that were left here: -Be careful when following anything listed here (above or below), as doing so may remove or damage any other Oracle-installed products. - For 64-bit Windows (x64), you need also to delete the HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\ORACLE key from the registry. - Clean-up by removing any related shortcuts that were installed to the Start Menu. - Clean-up environment variables: - Consider removing %ORACLE_HOME%. - Remove any paths no longer needed from %PATH%
This set of instructions happens to match an almost identical process that I had reverse-engineered myself over the years after a few messed-up Oracle installs, and has almost always met the need.
Note that even if the OUI is no longer available or doesn't work, simply following the remaining steps should still be sufficient.
Delete OracleDBConsole key ( delete this value) Also it may happen that you have previously created database with the same name and have removed it but the traces of it still remain - so open /etc/oratab file in edit mode and remove the line containing SID that is causing an error message.
Another place to look would be $ORACLE_BASE/oraInventory/ContentsXML/inventory.xml - this file could also contain an entry with the offending SID. You can also try deleting the SID in question here, steps - ORADIM -DELETE -SID
taken from here
we don't need to uninstall all program. Edit global database name. just change the orcl to orcle[arbitrary]
if you are in Linux environment
with root access go to /etc/oratab comment or delete the SID