Database Struck in single user mode and cannot drop

Execute below script to find SPID which is holding the process

Use Master

GO

Select * from master.sys.sysprocesses

Where spid > 50

            And dbid=DB_ID (‘DBName’))  -- replace with your database name

Once you identified the spid to KILL, you can simply execute:

KILL 85 – replace the spid with the one returned

Then try to bring it back into multi-user role

ALTER DATABASE StuckDb SET MULTI_USER
GO