The way it is done is the guilty party is reduced in rank to an E-1, then sentenced to incarcerations as appropriate, then, at the conclusion of their incarceration, then are given a DD.
If they are convicted by a GCM, they can be confined, be fined, or dismissed from service. Even if confined at a disciplinary facility dropping them from the officer rolls isn't automatic nor is reduction. Dismissal is a punitive sentence that may or may not include forfeiture of all pay and allowances and confinement but includes a removal from officer rolls. Depends on the court. But the result is similar to a DD.