Proceed cautiously. You don’t want MySQL’s internal structures to become inconsistent with what’s on the disk.

Run the query SELECT @@DATADIR; to find the directory that should contain a folder for each of your databases, including one called abm.

Contrary to the advice offered in the other question, don’t delete the abm folder once you find it. Instead, leave the folder there, and move the files inside it somewhere outside the datadir where MySQL can’t see them.

Then try again to drop the database the normal way.

Finally, restart MySQL to be absolutely sure that its internal structures are consistent with the disk files, by reviewing the log for errors. If the server restarts with no errors, and the database is no longer listed, it should be safe to delete the stray files you copied out of harm’s way, above.