Where does the "drop" terminology come from (hopefully not your recruitment counselor)? PNMs do not have the power to remove chapters from their schedules. Instead, you're putting the chapters in order of preference so panhellenic knows where to send you on the off chance you're invited back to more chapters than there are slots in the next round
just a quick note for any future PNMs who may read this! No one wants to be that girl embarrassing herself complaining that she keeps having to go back to a chapter she claims she dropped/cut/etc.