Give go, as a phrase, generally means to allow someone to proceed or to grant permission to do something. The antonyms for this phrase would be deny or prohibit. Deny, meaning to refuse or reject a request, or to declare untrue, would be the opposite of giving permission. Prohibit or forbid, meaning to not allow or make something illegal, would also be an antonym for give go. Another possible antonym might be restrain, suggesting that the speaker is attempting to hold someone back or prevent them from taking action. In any case, give go implies permission, while antonyms such as deny, prohibit, or restrain suggest refusal, disapproval, or the exercise of authority.