Select the database name from the drop down list... The database will then appear in the main page.
Go to the bottom of the list of tables and you will see a link saying "select all" click this and a tick will appear in the checkbox next to each table. There will be a drop down list at the very botton of the list of tables. From there select drop.
This will then brop all tables from your database. Click reload mysql from th enext page and click home. Now select your dataase from the list (at the left) again. It will again open in the main window, but this time there will be no tables. There should be a link "drop database [databasename]" If you click this your db will be removed. In some versiond of phpmyadmin it will ask you to confirm.
I am assuming you have enough permissions to remove it, because you created it.