Work through the asset in the assets section and on the screen that presents the option for "I sold or otherwise disposed of this asset" select that option and finish working it through.
If this is rental property that you owned and depreciated, understand that rental income/expenses, including the sale of the property is not reported on SCH C. It's reported on SCH E and the same guidance as above applies for reporting the sale in the SCH E section of the program.
