To remove each fitting, secure the outer shell in a vise or such. Use an open-ended wrench or flare wrench (better), to unscrew the mandrel tube from the ID of the hose. It is a normal right-hand thread. Once out, unscrew the hose from inside the shell. That is a left-hand thread, so turn as if you were tightening a bolt to unscrew.
Factory instructions for the fitting may be document "Gates Field Attachable Coupling Installation" (search), but note the shell there screws onto the hose OD with right-hand thread.