I can't believe this question isn't answered yet...
To remove your schema, please do the following:
1) shutdown mysql (on my MacBook I use):
launchctl unload /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist
2) Go into your DATA directory of your MySql, example:
cd /usr/local/mysql/data
3) The database over there is stored as a directory, just remove the dir with it's contents using rm -rf command:
rm -rf YourSchema
4) Start MySql, on the MacBook it's under:
launchctl load /Library/LaunchDaemons/com.oracle.oss.mysql.mysqld.plist
5) Login to your GUI (or whatever ADMIN tool you have), and then refresh.
6) It's gone.
7) Now, when you restart MySql you'd get errors in the logs saying ".. not found etc..." these will not stop the server from starting, to fix those, using the MySQL Admin tool, create a Schema with exactly the same name as the old one and then DROP it, this resolves the issue.
8) Restart MySQL, check all logs, all should be fine.
I hope this helps.