Is there a way I can change my username without needing to ban this account and make a new one with the right username? (Or forcing someone to get me supporter?)
If you are only after minor capitalisation or grammar/spelling changes, you can email accounts@ppy.sh to request a free name change. Otherwise there are various supporter giveaways like the one by Wowcake at community/forums/topics/1536587?n=1 and others that you can find on the forum