Wayne notices that Time Machine is taking a ton of space on his external hard drive. How can he minimize that? Time Machine says it's full. Leo says that he can adjust the amount of space Time Machine uses, but it can get a bit finicky when he messes with what Time Machine thinks it needs. Go into the System Preferences pane and there he can go into options and delete or disable the local backups on the main hard drive. That'll clear out some space. Time Machine should do that. It also keeps a local backup image and should delete the older ones as it does. The safest way to do it is to go into the Time Machine app itself and manually delete the backups. Go into the gear (settings) and he can do that there.
He can also start over on the external drive, but he would only be backed up from today going forward. One thing he can do is make sure it's not backing up movie and music files, since Apple should already be backing those up online.