Is it possible to change a nickname here?

Maybe moderators can change my username to EmilyGraceSeville7cf? If it’s not possible, can be my account deleted by admins (to let me create a new one with a new nickname, I don’t wanna two my accounts exist at once)?

You can change your name but your username is based on your Replit @mention name. Ask tends to use the @menti0n name (username in the screenshot) far more than your “Name”, so the only practical way to change your name on Ask is to change your Replit @menti0n through the CLUI and then log out and back in to Ask. However, I would not recommend changing your Replit @menti0n as you can only do it once and it messes up all previous @mentions on Replit.