Just wanted to pass this along as it might save some others some headaches.
1) Delete SketchUp folder from Applications folder
2) Delete SketchUp folder from Library
3) Delete SketchUp folder from Application Support folder
4) do a search of the Library folder for “SketchUp”
4a) delete any files found in this search
For SketchUp 2016 and SketchUp 2015 the above folders and files will have the version in the folder or file name i.e. SketchUp 2016.
I had done all but the 4th step but missing this step cause orphaned files to be left in the system which caused some staring behavior with some SketchUp pluggins.