An Air Force squadron commander has been relieved of his command after five nuclear weapons were mistakenly loaded aboard a B-52 bomber and flown cross-country from North Dakota to Louisiana last week. Five 150-kiloton warheads were attached to cruise missiles that were flown from Minot Air Force Base, N.D., to Barksdale Air Force Base, La., to be dismantled, but the warheads should have been removed.