Weird- I typed out a post and it just disappeared???
Here we go again.... My missus is ill. Been going back and forth to hospital. Got her home and thought that would be it. Er, nope. Have to deal with the kids trying to kill each other, doing the cooking and other jobs that I don't usually have to do (so it's all awkward and slow).
Between the earlier attempt at this post and this one, she's asked me to go out and put petrol in the car in case she needs it whilst I'm at work tomorrow.
I would peen it over first, as if you just try and use sandpaper, it'll take ages and you'll probably end up rubbing the good area around the damage quite a bit as well. So, tap it flat (gently) and then use a small file (not paper) to trim the rest down, before doing the last tiny bit with paper.