When I use my unban command, it floods the text box with like ten messages saying "Joe removed Bob from the banned list." The code follows, can anyone tell me why?

UnBan()
set desc = "() Remove banned keys and IPs from the banned list."
set category = "Owner"
var/removal = input("Remove which IP/key from the ban list?","Unban:") as null|anything \
in banned
if(!removal) return
for(var/mob/M)
world << "[src] removed [removal] from the banned list."
banned -= removal