BobHartung wrote:
Before going crazy make sure that any images in the LR 5.7 library also exist in the LR 2015 CC library.
Then you can uninstall the LR 5.7 files and folders, again being sure that you are not deleting the actual images.
Whenever I am doing this sort of thing, I make sure to keep a copy of any images on an external drive until I am satisfied that I haven't lost anything.
Yes, if you did anything with the 5.7 version after installing and opening the upgrade those changes will not be in the CC catalog.
I had that problem with my Lightroom 6 upgrade. I was wondering where my last import had gone. Turned out the upgrade had not changed the icon on the widows 8 page but did on the desktop. Neither said what was till opened.