Be aware that; if using a "step drill" to remove pop rivets that the resultant hole will no longer be suitable to replace pop rivets, as you will enlarge the hole - it is better to use a twist drill sized similar to the correct size of drill required for initially fitting the rivets.
The removed rivet flange will feed onto the drill bit, like a "collar" which can be removed from bit with pliers. Bit fussy but better job not damaging the original surface.

You only need to drill the the top off and punch them out ..Or use same size drill on hammer .