Delete Key from KeynoteTable

I am working on an Add-in to edit the keynote table directly in Revit. I can sucessfully read the contents of the KeynoteTable, and I can select entities in it.  I am looking to implement a way to delete keys.  I see that it is KeynoteTable.DeleteEntity(Schema) I am having difficulty getting the schema of the entity that I want to delete. When I use KeynoteTable.GetEntitySchemaGuids() it returns a list with 0 entries.

Am I going about it the wrong way to get the schema to delete an entry in the key table?