I "pinch" the sides of one side of the butterfly clasp with my thumb and forefinger, and open that up. I then repeat on the other side. I think it is important not to twist the buckle open, as this may strain clasp and prevent it from closing properly.
I would also advise against wearing the bracelet "loose"... this will cause premature wear on the bracelet links.
so the watch stays in place on your wrist and doesn't slide or spin on your arm. If worn too loose, the weight of the watch head will cause wear between the links. I have seen several 5036s with "sloppy" bracelets which have worn quite heavily.
MW