The only way I know to get rid of a custom perspective is deleteing the RAC cache.
If you do not want to delete the complete cache I can look up which files are holding the information of the user perspective.
This is just a hack that worked for me!
Go to the following directory: RAC\xxxxxxxxx\.metadata\.plugins\org.eclipse.core.runtime\.settings
Open the file org.eclipse.ui.workbench.prefs
At the end of the file you should find 2 lines defining your user perspective.
Deleting these 2 lines helped me to get rid of the perspective.
How can a user define a perspective? Perhaps you mean a user preference. For this there is a utility:
preferences_manager -u=%TC_USER% -p=%TC_PASSWORD% -g=%TC_GROUP% -mode=remove -scope=user -preferences=