You need to enter this transaction in the Rental Properties and Royalties section of the program.
Indicate that you sold or disposed of the property in Property Profile and then, if you have not already done so, enter the property in Assets/Depreciation. During the process of entering the property, you will again have to indicate that you sold it (check the appropriate box).
You will ultimately arrive at the screen in the screenshot below (obviously, click the Yes button).