delete site content type error

I'm trying to delete a site content type.  I ran a powershell script to check for usages, and the only usage listed is on the site collection.  I had already removed all references in all document libraries.

But I'm receiving an error when I try to delete the content type at site collection level.  Its saying its still in use, but its not.  I checked all recycle bins and there's no traces of it.

is there a powershell command I can run to allow deletion of this content type?

thanks!