Upon noticing a putting green golf ball mark simply dig your pitch repairer into the undamaged outsides of the golf ball mark.
Gently pull the surrounding grass towards the center of the golf ball mark. Avoid pulling up as this damages the grass roots.
Putting Greens are amazingly elastic and the grass will stretch over the golf ball mark.
Work your way around the outside of the golf ball mark pulling small pieces of grass over the center of the mark on the putting green.
When you have completed a full circle use you putter club bottom surface to gently tap the stretched grass into a flat surface over the golf ball marks.