Drop all tables in a MySQL database
mysqldump -u[USERNAME] -p[PASSWORD] --add-drop-table --no-data [DATABASE] | grep ^DROP | mysql -u[USERNAME] -p[PASSWORD] [DATABASE]
Edit: On second thought, reading MySQL docs it says that...
Important
When a database is dropped, user privileges on the database are not automatically dropped.
I should probably test this but it sounds as though a DROP [DATABASE] && CREATE [DATABASE]
will do the trick for you.