A FlyerTalk Posting Legend
Join Date: Sep 2012
Location: SFO
Programs: AC SE MM, BA Gold, SQ Silver, Bonvoy Tit LTG, Hyatt Glob, HH Diamond
Posts: 44,354
I've never had an issue doing that. In fact, as long as you cancel before check-in closes, you can offload yourself (go back to OLCI and check the box for "not traveling") and then refund it online.
If you miss the check-in cutoff, you'll likely need to call.