There are a few options to enter the sale in ProSeries.  Here are a couple of them:

1. Manually divide the Sale Price up between the building/land Asset the improvement Assets, then sell each Asset with its respective sales price.
2. Or on each Asset Entry Worksheet, enter the sales date but NOT the price.  That will stop the depreciation, but not report the sale.  Then manually combine the Basis and Depreciation, and enter the sale on the "Enterable 4797".