The word "un-barring" is a compound word, which means removing or lifting a restriction or prohibition. The term "barring" implies the act of prohibiting, excluding, or denying access to something or someone. So, the antonyms for "un-barring" can be words that denote the opposite meaning, such as "barring," "exclusion," "ban," "prohibition," or "veto." These words signify the act of preventing or denying access or participation in an activity or event. Therefore, if we use the antonyms of "un-barring" in any sentence, it would indicate that access or participation is not allowed, and there is a restriction in place.