The DROP DATABASE Statement is used to drop or delete a database. Dropping of the database will drop all database objects (tables, procedures, views, function etc.) inside it. The user should have admin privileges for deleting a database.
DROP DATABASE database_name
If you want to drop database TestDatabase, the statement would be like
DROP DATABASE TestDatabase
Caution: Be careful before using this operation because by deleting an existing database would result in loss of complete information stored in the database.