The sale of business property would be reported on a Form 4797. If the only business property sale or retirement during the year was the one you mention, you can delete that form and that should resolve your issue.
Follow these instructions:
1. Choose the Tax Tools option on your left menu bar
2. Choose Tools
3. Choose the Delete a form option under Other Helpful links
4. Find the form(s) 4797 in the list and delete it - there may two forms so delete both them if necessary