Land is not depreciated. As such, you do not need to change anything on how your report your rental unit on your tax return. Do not report the sale in the rental area of your return.
Instead report it under investment sales. You will have to allocate part of the original land cost to the sold parcel, for it's cost basis, to determine your capital gain or loss. On your own records you also adjust the rental unit land cost for when it's sold in the future.