Execute this SQL Server script to kill all connections to a database. Be sure to replace "DATABASE_NAME_HERE" with the actual database name.

create table ##killstmts(
    stmt varchar(15)
);

insert into ##killstmts(stmt)
    select 'KILL '+cast(spid as char(4))
    from master..sysprocesses as p
    inner join master..sysdatabases as d
        on p.dbid = d.dbid
    where d.name = '<DATABASE_NAME_HERE>'; -- Provide database name here to kill all connections

declare @KILLSTMT varchar(15);
declare killcsr cursor
    for select * from ##killstmts;
open killcsr;
fetch next from killcsr into @KILLSTMT;
while @@fetch_status = 0
    begin
        -- print @KILLSTMT
        exec (@KILLSTMT);
        fetch next from killcsr into @KILLSTMT;
    end;
deallocate killcsr;

drop table ##killstmts;