Home>Settings>Live and there is a toggle switch for "Friends can challenge me no matter what" is maybe the easiest way. There is probably something similar for Daily. I'll poke around and see if I can find where the challenge limits are, but no promises...
I just accidentally started a game and had to abort... Good luck!
I have several Chess Friends that can no longer challenge me to a match because they exceed the upper limit I had set on challenges. Can someone please remond me how to raise the limit?