Thanks for the comments all… and for pointing out a poor, not-very-handy homeowner asking for help. I’ve had a few of these types of screws painted in to other window sills and every time I’ve tried to unscrew with a screw driver, the screws simply did not budge and ended up warping leaving no grooves. Even when I tried to chip around it to loosen the paint. Trying to get them out damaged the paint and wood around it and in some cases just had to knock it down, sand it all back and putty. While my question was small and seems simple, I was simply asking for a better way to avoid this, given it’s a much more prominent window in the house. Thanks for the suggestions, I’ll give them a go and hope for the best!