Place a towel in the bottom of the bathtub to protect the tub's finish while you work. Working from inside a tub is less awkward than working while leaning over its side.
Lift the toe-tap stopper with your fingers until it will lift no farther. Turn the stopper counterclockwise.
Pull upward on the stopper as you turn it counterclockwise if the stopper only spins instead of unscrews from the drain. If the stopper merely spins while you turn it, then its threads are most likely stripped, and the pressure from pulling the stopper upward while turning it should be enough to remove it from the drain.