To remove a recurring panel instance from a drawing, go to
Ribbon: DM Electrical->Distribution Equipment-> 
Remove Recurring Panel Instance from this Drawing
Pulldown Menu: DM Electrical->Distribution Equipment->Recurring Panel Instances->Remove from this Drawing
You will be prompted to select the recurring panel instance to remove from the drawing.
Select recurring panel instance to remove from drawing:
After you select the instance, it will be removed from the drawing but remain in the database.