Something like this is likely to work

use master

kill 75 -- the connection to the database in single user mode

use [MyDatabase]

alter database [MyDatabase] set multi_user with rollback immediate

If that doesn't work, try this:

use master

kill 75 -- the connection to the database in single user mode

alter database [MyDatabase] set offline with rollback immediate

alter database [MyDatabase] set online, multi_user with rollback immediate

Another thing you could do is disable the logins that have access to the database, kill the active database connection, and then alter the database.