I haven’t run into anything like that but for some reason the search engines are taking time off...
I remember there was no love lost between Hoover and the Kennedys but I don’t remember a firing by either LBJ or JFK..It couldn’t have been very successful if he was still in office when he died as I seem to recall also..
The Hoover files were burned after he died. Bobby Kennedy hated J Edger and Lyndon learned to live with him. I don't know how far the legal process went but both o he announced that Hoover would leave. As others here noted Clinton did fire Sessions at the request of Janet Reno, with out a problem.