TheTVAddict.com interviewed Edge (as Adam Copeland) at this link. In it, Edge explains the decision to cut his hair:
I was just tired of having long hair. I just chopped it off before I got inducted in the Hall of Fame for WWE in April. The day before, I just thought, “Why not come out on stage with a new haircut?” So I did. And I thought if Dwight’s an ex-Army Ranger, at some point he’s had short hair so it’s not that far a stretch that he would have short hair again. Then in the context of timeline-wise, you can get your hair cut any day and look different. I don’t know. I just wanted to do it.