It's a matter of preference but should be slightly better to leave the scapes on until they're brown and then cut them or leave them. The hollow cut stems can collect moisture and insects/mites so it may be better for the plant to leave them intact for longer. Some people leave the dead scapes on so they can do bud counts when less busy. What you definitely should not do is pull the scapes off if they don't release with a slight tug because otherwise you may damage the crown and create an entry for diseases and pests.
