James, make sure there is a WindowsApps folder in C:\Program Files which has your existing apps.
Then make sure the ones in the WindowsApps folder on the hard drive are uninstalled or exist presently in the C:\Program Files\WindowsApps folder. Those apps will stay there when you move the Apps to another drive, and only the future apps you install will go to the new location. To move the existing apps from C you must uninstall them and then reinstall to the new location.
To delete the WindowsApps folder on the hard drive try Take Ownership first using this handy tool that will install to your right click mouse button: https://www.askvg.com/add-take-ownership-option...
If that's not enough use Unlocker:
http://www.emptyloop.com/unlocker/
keep me posted on your progress as I will be here to help until the case is resolved.