This does seem unstandably weird unless you havent tried to highlit them and simply press cltrl+backspace. if you have tried this it is wierd. mabey because your movie is long it sort of malfunctions. there is another way to delet. highlit the Intro/outro then above the time line there is a menu that has undo reado ect...
also  there is the delet butten or "X" click this when the object is  highlited and it should delet it i've never had a problem deleting things.
GOOD LUCK!                                                       -Chip Comando