Remove Masonry Nails from Concrete floor
Loosen it by tapping it lightly to moderately hard, back and forth--side to side, then when it is sufficiently loose pull it out. Tap parallel to the longer dimension of the rectangular cross section.
AFIK this type of nail (cut nail) is a not a hardened steel nail for driving into concrete. It may be hardly into the concrete and you might be able to pull it out without any tapping. Try a pry bar or channel locks without hammering.