You can not delete or merge accounts. If you have more than 1 account just pick one and use that going forward.
It's common to end up with multiple accounts. First LOG OUT of whatever TurboTax account you're logged into right now. Then use this TurboTax account recovery website to get a list of user ID's for an email address. You can use the same email address for 5 accounts. Run the tool against any email addresses you may have used
https://myturbotax.intuit.com/account-recovery/
