If you want to attempt recovering your old account, refer to - Account Recovery & Creation (ensure you read the relevant stickies).
As for deleting said account - staff don't delete accounts. However, the staff can apply a DNT (Do Not Trade) to the account if you're able to prove you are the original owner.
NB: a DNT is akin to being banned - unable to participate within the market, alongside a few other added on rules.