How does one go about removing the wiper arm assemblies from a 1972 Dodge Dart?

Im almost ready to rattle can the cowl area and I dont want them in the way.

There is a tool for this but , a craftsman square shaft screwdriver will work.
take screwdriver and protect the blade from damaging the metal (rag, credit card etc.)and put it under the outside edge of the round nub and gently pry up. It will help to wiggle it a little bit while prying..

Much as you may be tempted, do not use wd40... it's almost impossible to clean up before paint! as said, move the tab and work at it!