Please make sure your usual database is set as the active & default database - just clicking on it wouldn't be enough:
Guide: Database ManagementNext turn on 'Enable Logging' in PokerTracker 4 via 'Configure -> Options' and then restart PokerTracker 4.
Verify your usual database is now active - it will be listed in the PokerTracker 4 titlebar.
Try and delete the database with the other hands.
If you still cannot delete that database then in PokerTracker 4 select the 'File -> Create Support Bundle' menu option.
Save the support bundle file to your computer and then attach that to a
Support Ticket where we can check your logs.