MoeFoe: I reset my bag with the starter hybrid I had, but I couldn't save the bag.
Apparently WGT ignores the closest workaround, so here it is:
Get into your inventory and unload and reload other clubs in your bag, not touching the "rental" spot. When the "SAVE" button becomes green, just press it regardless of the status. (*) Next, sort your bag as you like it, including the former rental club. SAVE and play happily!
(*) You may have to leave the inventory and come back...