If you backup the database, drop it, recreate it, and restore the data you would be looking at maybe five minutes of downtime. The issue is cpanel creates databases and assigns permissions with root access via the cpanel button. Phppgadmin uses your cpanel username which doesn't have full root permissions. There's a lot of subtlety that is lost because cpanel didn't design their interface with root access for every possible thing you might want to do.