Most unbolted refers to something that is the most easily accessible or open. The antonyms for this phrase can vary depending on the context in which it is being used. For example, if most unbolted refers to something that is easily accessible, then the antonyms would be closed, inaccessible, or locked. If most unbolted refers to something that is open, then the antonyms would be closed, sealed, or shut. Alternatively, if most unbolted refers to something that is exposed, then the antonyms would be hidden, covered, or concealed. Overall, the antonyms for most unbolted will depend on the specific context in which it is being used.