How can you most effectively erase my chest and back acne quick and easy?

Serious Rx: Acne on the trunk usually requires systemic treatment. Your physician knows how. If something like tetracycline 500 2x/day is insufficient, consider a referral to a dermatologist for isotretinoin. This is neither quick nor easy, but it works. If you're responsible for someone with acne, please get them treated effectively now; not doing so will lead to a lifetime of regrets.