Permanently deleting Designs is a poor idea. All designs should go to a deleted design location from which they can be reloaded or restored to their original location. A roll off of deleted designs on a calendar basis would be acceptable. For example, if I haven't wanted to recover it in 6 months, it could be removed. That should be configurable, with a NEVER option.
The rationale for this is that people make mistakes. Software makes mistakes. When a person intends to delete an old design but deletes a new design (not versions) or when the software has a bug, the design should be recoverable.
For example, I had a design that I wanted to move to a better location in my project structure. The design was unmoveable, apparently because of some not yet implemented feature per an Autodesk authored forum page that I didn't discover until later. I could have exported it and restored it but instead I loaded the design and Saved As to the desired location. Then when I deleted the design in the original location after confirming that it was the new location, the design disappeared in both locations, losing about 60 hours of work for me.
