You can use below query, it picks all the connections from a host (ABC in this case) from sys.sysprocesses; creates a common statement to kill them; and then executes the statement.
Replace 'ABC' with hostname;
you can see which sessions it has killed by deleting the comment from 'print' section of the script
declare @SqlCmd varchar(1000), @HostName varchar(100)
-- Set the hostname name from which to kill the connections
set @HostName = 'ABC'
set @SqlCmd = ''
select @Sqlcmd = @SqlCmd + 'kill ' + convert(char(10), spid) + ' '
where hostname= @HostName
DBID <> 0
spid <> @@spid