First I grab the Search Service Application GUID ID.
1. Log into the Central Administration Server
2. Open up SharePoint 2010 Management Shell (PowerShell)
3. Type: Get-SPEnterpriseSearchServiceApplication
4. This will list all properities of the Search Service Application.
5. Right click and select “Mark”, highlight the Search Service ID and right click again to paste into the clipboard.
Second we are going to remove the Search Service Application using STSADM
1. While still logged into the Central Administration Server open up a Command Prompt using Admin Rights
2. Change directory to: c:\Program Files\common files\Microsoft Shared\Webserver Extensions\14\bin
3. Now type the STSADM command
stsadm -o deleteconfigurationobject -id [Search Service Application GUID ID]. Just right click in the window and paste the GUID ID.
4. Hit Enter!
Unable to Remove Search Service Application in SharePoint 2010