After you decide to leave the DEP, you are likely to face a lot of pressure from your recruiter. Keep in mind that threats are not true and that separating from the DEP will not have bad consequences. It is true that the law says that every male must register for the draft within 30 days of his 18th birthday. At present there is no actual draft. These options are not available to you at this point.
Some people register but place messages stating their opposition to war in the margins.
This is a form of protest and does not necessarily have any legal significance later if you should apply for a deferment or exemption. Instead, the draft agency has relied on a series of coercive federal and state laws that deny benefits to young people in order to muscle them into complying. Both registering and not registering have their risks. On the other hand, persons who register may find it more difficult to avoid the draft later. You have to make a decision for yourself based on what you think you can live with.