Dears , we faced a very tough problem last few days . which is we wanna delete search service application but we didnt succeded , using powershell or central administration we couldnt do it.
but after search Thanks To Jesus , finally we found this link http://donalconlon.wordpress.com/2010/08/27/deleting-the-search-service-application/
the solution is to remove the service using the old way the Stsadm.
Long live stsadm , you will be in my heart forever 🙂