What can I use to get rid of whiteheads on my nose and chin I have oily acne prone skin and I use benzyl peroxide 5% acne ointment which has cleared my pimples but is making my whiteheads worse

You seem to have the acne germs under control, correct? Just plain whiteheads are normal skin oils collecting in the pores. Working up a good sweat and then flushing the pores in a very hot shower is the traditional solution for non-infected pores.