How to record the partial sale of a rental property (Sub-divided & kept some of the adjacent land but sold the building)

In the same year, I subdivided 36 acres that had a rental building on it, and sold only the building with 6 of the acres, and kept the remaining 30 acres.  I had originally entered this real estate as one asset (36 acres plus the building).  How and where do I enter this partial sale of my real estate please?