If you are needing to edit your return and you have submitted it yet, you would just log back in and click Review My Return.
If you need to edit it after it has been submitted, you would need to wait until it has been Rejected or Accepted. At that point, you would need to Amend your return. Please see below on how to complete an Amendment:
You can amend returns that have been accepted by the IRS. If your return is pending, you won't be able to make any changes until it's accepted or rejected by the IRS. If you don't know your e-file status, we can help you check it.
Select a tax year for specific amending instructions.
Keep in mind: You have 3 years from the date you filed your return (or 2 years after you paid the tax due, whichever is later) to file an amended return, which means you don't have to get it done by the April 15 filing deadline.