I'm planning a challenge run but must create a new account to try my challenge. I looked at the other forum but found no answers, so I'm asking if there is a way to delete my data in Run 3 Flashpoint or create a new account to play Run 3 in.

Hi - I can't recall if you're in the discord or not, if not, I recommend you join as there's people more knowledgeable than me with flashpoint there. As for what I can say - if you go to the guide I wrote here it contains instructions about playing the game locally using a standalone local flash player application. Hope I helped.