"cannot drop database because it is currently in use"

A common mistake is usually made when executing the "drop database db_name" statement is forgetting to terminate the current session connected to the target database. A quick solution is to switch to master db and then drop it.

use master
drop database db_name

Most of the time, this can succeed. If the same error message still pops up, disconnect query analyzer or management studio from the SQL Server and reconnect to it and run the above t-sql command again.