If you have an Advanced license you would use the Erase tool.
If you don't have an Advanced license you would have to use the Union tool. Since you only are dealing with two feature classes the Basic license is sufficient, but you would need a higher license to process more than 2 feature classes at once with this tool. You should consider using the Integrate tool on a copy of the feature classes prior to using the Union tool if you do not think the topology of the two layers matches very well.
The output of the Union tool will have two fields for the ObjectIDs of the two input layers. You would only retain those polygons where the ObjectID field of the Sales layer has a value of -1, meaning there are no sales properties in that location and only the original company ownerships exist there. Select that set of polygons and export them to a new feature class or do the inverse selection and delete all of the sales properties.
You may want to use the Multipart to Singlepart tool on these new polygons, since by default the Union tool preserves all parts of the original polygon that are not cut by the other polygon as one multipart feature even if the cut results in several parts that do not touch each other. Be prepared to deal with sliver polygons if the topology of the two layers is off and you may need to use the Dissolve tool with the multipart option unchecked if there was bad topology internal to either of the two layers.