Move deleted references into a new library

I have a library of 4,000+ references that I need to clean up but since all of the references have been used for publications at some point, I want to move the deleted references to a “Retired” library.  The easiest way would be to delete the reference from All References, then move the deleted references into a new library. However, the only action for a reference in the trash bin is to restore or delete permanantly. Does anyone have any other suggestions?