Have 1950's floor furnace, I was told to turn thermostate as far down as it goes to stop it from heatng house but heat is still coming out . What do I do ? My wall a/c is working overtime.

Do you have a wall mounted t-stat? It may be bad. Take it off and see if the furnace stops.

Is it a lot of heat? Or just a small amount? could it be some heat coming from the standing pilot lite?, its possible,,
If so turn off the gas at the gas valve in furnace