A couple of weeks ago I run into problems with a SharePoint 2010 Search SSA which apparently did not work anymore. Nothing helped to get it working again so we decided to delete it. Unfortunately doing this through the UI did not work nor did using Powershell. So we decided to just delete the associated SQL database. Afterwards I needed to remove the reference in the SSA administration screen. Luckily there is a stsadm command to do this:
Stsadm -o deleteconfigurationobject -id “GUID identifying the Search SSA”
To get at the GUID for the Search SSA – you can use the Get-SPEnterpriseSearchServiceApplication Powershell command.
This is probably not the recommended way of doing this but if nothing else helps you can still revert to this method.