When I first moved into the area I had the same thing happen. He’d knock on my front window and ask for money (sometimes he’d say he’d done some work in the yard or something). Nothing you can do but keep saying no (I also never have cash, but even if I did, I’m not going to open my front door to someone I don’t know). I found having blinds on the one window next to the door has helped. In the end, the guy seemed harmless, so I just kept saying no and he hasn’t been back in a few months. Sorry that isn’t more helpful.