How to get rid of the genital rash ?

See your doc: It is hard to know without an exam. Diagnosis can be difficult even when looking at rashes so you need to see your doc, PA or nurse practitioner.

See doctor: to have the rash checked and diagnosed then it can be treated.

Depends: Could be a lot of things. If it's jock itch (fungus) some topical antifungal like Clotrimazole will work. If it's herpes, there's not a lot you can do if it's been more than a couple days. There are other possibilities that need still different treatments. Better have it checked out.