1 clotrimazole cream takes days to treat ringworm?

A few weeks. Use it for a few weeks until you can't see the ringworm and continue another 1 week after that. It will also depend on how big the rash/es is/are.
2 weeks. Use the lotrimin/ Clotrimazole cream 2x/day x 2 weeks (at least) for maximal effect.