Allow users to remove Elevation Surfaces from TOC in a map

[DuncanHornby]

Latest version of ArcPro 3.1.2 allows you to add elevation datasets to Elevation Surfaces, you can remove the dataset but currently it is not possible to remove the Elevation Surfaces node in the TOC tree. Please add the ability to remove that too. Example is shown below.

Example showing how you cannot remove the Elevation Surfaces node