If someone voluntarily wants to wipe away memories, so be it. The difficulty is that propranolol affects short-term memory and not long-term memory. Eventually there may be technology to affect certain memories only instead of wiping out a lot of short-term knowledge. But for now, I don't think propranolol can selectively delete memories from human brains.
Aside from treating traumas it does not sound like a good idea to dampen a persons memory or mess with it in anyway. It could lead to a lot of problems with the person, and create a sense of loss in them and they will never know why they feel that way. It just seems wrong.