The antonyms for the phrase "blocks off" can be understood by focusing on the opposite meaning of the words. The words that exactly convey the opposite meaning of "blocks off" are "opens up" or "uncovers." When we talk about "opening up," it means to remove any barricade or to make something accessible while "uncovers" refer to the removal of any cover or obstruction. In other words, instead of putting up barriers, it means to allow access or free movement of people or things. Therefore, if one wants to avoid blocking off, then one needs to ensure that no barriers or obstructions exist, and the way is clear for easy accessibility.