So you should make it part of your Revit standard that no one can rename Workset1 - ever.
As usual, this is something that Steve already knew, and already told us. Thanks Steve!
One other habit I have is to never rename Workset 1 because Revit won't let us delete it. It's the "original" workset and Revit just doesn't let us delete it.
Revit OpEd: Delete a Workset's Contents?
An old discussion on AUGI also touches on the issue:
2009-04-16, 12:27 PM
I just followed Shruti's instructions and got the same error. For me it says I am deleting "non-editable Workset 'Workset1' " Any other ideas?