Unbelts is a relatively uncommon word which means to undo or remove the belt that is fastened around one's waist. If you're struggling to find synonyms for unbelts, a few possible options include untie, unclasp, unbuckle, unfasten, or undo. All of these words convey a similar action of loosening or releasing something that is secured or held in place. It's important to choose the right synonym based on the context in which you're using it. For example, if you're describing someone taking off a belt, you might use unbuckle or unfasten. Alternatively, if you're describing someone untying a piece of cloth or rope that is tied around their waist, untie might be a better choice.