The database is in single-user mode, and a user is currently connected to it.

 

 

just use this command in query window

USE master;
GO
DECLARE @sql nvarchar(MAX);
SELECT @sql = ' KILL ' + CAST(session_id as varchar(5))
    FROM sys.dm_exec_sessions
    WHERE database_id = DB_ID(N'[DataFeed_BLM]');
SET @sql = @sql + N' ALTER DATABASE [YourDB] SET MULTI_USER;';
EXEC sp_executesql @sql;
GO

it will shows the process IDs, kill the process id using this command

kill (process id) my process id is 64
like
kill 64

Option 2 :

This command is helpful too

SELECT request_session_id FROM sys.dm_tran_locks WHERE resource_database_id = DB_ID('YourDB') 

Option 3 :

You can also use this command to check the current connection

use master
GO

select
d.name,
d.dbid,
spid,
login_time,
nt_domain,
nt_username,
loginame
from sysprocesses p
inner join sysdatabases d
    on p.dbid = d.dbid
where d.name = 'YourDB'
GO