I have an electrical box that has knockouts but they aren't spot welded like usual, these look like solid circles. I have attached a picture of what they look like from the outside, what is the best way to remove these? Thanks!
I use a screwdriver and a large pair of pliers. They did a nice job of painting. Place the tip of the screw driver on the top or bottom, the supports are on the left and right. Then I hit it a few times with a hammer and it starts to bend in forcing an opening. When I get it big enough I normally use a heavy duty needle nose pliers and then bend it back and forth a few times and it breaks free. If I want the larger ring out I use a lock jaw pliers and it will come out without a lot of problems. The curve on the jaws will work against the other side giving me some mechanical advantage. I know there are other ways but this works best for me.
The usual method is driving a screwdriver with linemen's pliers.
It seems the factory punch isn't always (or maybe always isn't) within workable tolerance and isn't punched adequately. It can be easy to damage the collar for the smaller fitting when trying to knock out just the inner knockout. I always have 7/8" and 1 1/8" hole saws in my tool bag and if the ko's don't show movement after the first couple of well placed taps I whip out the cordless drill. Often they break free while drilling just the pilot hole.