Pivot bar is Missing

I'm afraid I can't tell you what your pivot bar is based on the provided photos. We can't identify missing hardware; this service requires a photo reference at minimum. Based on the design of your pivot shoe, there are about a million different potential compatible pivot bars. If you don't have an old one to use as a reference, then you're looking at a lot of trial and error and wasted money.

Do you have an identical window in the house that might use the same hardware? If so, remove one of those and let's use that as a reference.

Great, there's no rush on our end. We're here to help at your convenience.

Regarding removing the opposite end, it should just be screwed on. Make sure to safely remove the sash and place it on a flat, stable surface, then you can remove it using a screwdriver.

I also recommend taking measurements. The only thing you need to worry about is the distance between the screw holes (measured from the center) and the front tip of the pivot bar (the end that goes into the pivot shoe). Nothing else is as important as that. There's a chance we will have multiple different options for you that only differ in that one aspect, so it's good to get it now for comparison's sake.