How do you automatically delete a record in one table after manually deleting a corresponding record in another table?

I'm trying to do this with a global that is called after a successful deletion via a conditional statement that looks for default_success=1. I can write the statement in MySQL, but I can't seem to write it as a template global in DBMan SQL.

The global should perform a left join on the primary keys of the two tables where null records vs. non-null records can be deleted.