Unable to delete Search service application : Operand type clash

Something went wrong during Sharepoint 2010 installation.  There were a lot of error messages about Search service app.  So I decided to delete the existing one and create a new one.  I was able to create a new Search Service application and set it to be default.  However, I'm not able to delete the old one, not through Central Admin, and not through Powershell.  Here are the powershell commands I used:

$spapp = Get-SPServiceApplication -Name "<Service application display name>"
Remove-SPServiceApplication $spapp -RemoveData
When I run this, I get an error:
Operand type clash: unique identifier is incompatible with int
Any idea how I can delete the old one?  Or even delete all instances and provision Search from scratch?
thanks