Since the property was not rented in 2018, you can't add it in the rental section. You will need to have it entered on Form 4797 by following the steps below.
To add Form 4797 to your return:
- Select Take to my tax return, search for 4797, sale of business property (use this exact phrase) and then choose the "Jump to" link in the search results.
- On the Any Other Property Sales? screen, select the first checkbox and click Continue.
- Follow the instructions to complete the form.