Questions. in Slowing Down

What does the bright red box with the letters inside of it , Block User, Mean? Its on a lot of diaries I enjoy reading. A lot of these diaries I use to read regularly but now I can’t. How do I get rid of this box? Some of these folks are on my Bookmarks and Friends list. If I can’t leave a note I might as well take them off my lists.

Thanks for any help you can give me. Take Care Folks.