By mistake manually entered a recurring donation under the wrong account
Did any monies get processed when you added the recurring Donation? If it did (or did not) will depend on your Payment processor and what pathway you used in CiviCRM to add the Contribution.

If Monies were transacted -> then you'll not just want to Delete the Contribution and re-enter or you'll charge the Credit Card (or Bank Account) again. If you can add some more details to your original question then we can help you find a solution that will work for you.