There are 2 ways to delete forms in TurboTax Online. You can sign in and click on Pick up where I left off, then choose Federal (on the left) and Wages and Income (top menu). Scroll down through the list and locate the income form that needs deleting. Click on Edit/Add next to that section and look for a trash can icon next to the 'Unknown' payor, see image below.
Option #2 - https://ttlc.intuit.com/replies/3288508
