There is no single author universally banned from school library shelves. Book bans are highly localized and vary widely by school district, state, and even individual school. Different districts ban different authors and books for different reasons, often related to perceived sexually explicit content, violence, or promotion of certain ideologies.
To find out which authors are banned in a *specific* school district, you would need to research that district's policies and library holdings directly. News reports often highlight individual cases of book bans, but these are not representative of a national or even statewide trend.