You cannot cancel a return once it has been filed. After you click Transmit Returns Now, your e-file goes to pending status, where it will stay until it's either been accepted or rejected by the government.
Think of pending as "in transit" or "in limbo" – just like you can't cancel a letter that you sent yesterday, you can't cancel a return that's on its way to the government.
To submit the amended return you completed with another tax preparer simply mail it into the IRS. The amendment changes (amends) your original return, and you will receive the additional refund from the IRS once they approve it.
