If you're on Windows NT/2000/XP/2003, then the files will most
likely be located under
C:\Documents and Settings\<Your Username>\Application Data\Firebird\<random characters>.slt\cache
The easiest way to find out exactly which directory, however, would
be to start Firebird with the -P switch, and then choose "Manage
Profiles". You can then select "Delete Profile", which will bring
up the location of your Firebird profile and ask you if you what you
wish to delete. You can then cancel out of the delete dialog, and
close out of the Profile Manager.