Place a bucket or towel under the sink
Locate the pivot rod under the sink
Find the retaining nut holding the pivot rod in place
Loosen and remove the retaining nut
Pull the pivot rod out of the drain assembly
Lift the sink stopper straight up and out of the drain
If the stopper is stuck, wiggle it gently while pulling upward
Clean any debris from the stopper and drain opening
Reinsert the stopper in reverse order if needed