Orphanage

There is no way to simply quit the Army once you are on active duty. You are contractually, and perhaps morally, obligated to see your commitment through. However, you could be discharged from duty early if you are physically or psychologically unable to perform your Army duties.

Military Orphanage Home

You cannot resign your commission until you have completed eight years as a commissioned officer. Even when you have, you need to complete the resignation letter and send it to the appropriate command.
To apply for Resignation, here are things you should note. A soldier is ineligible to apply for the Resignation Form. Only a loved one, family, child, fiancé, sibling or close friend is eligible to apply, and you must do so with the consent of the deployed soldier.