I tried this just now. I renamed the folder to ".old" and when I restarted and looked at the sync activity, it still shows the same 605 old files trying to sync. If I double-click any of the files I go to http:// lightroom.adobe.com/libraries/ and see a message like this:

If I open LR on my phone, nothing happens, because these images are not on my phone. I deleted the app data and cache on my phone and restarted LR on my desktop and it's still showing the same 605 "old" files trying to sync.

You may need to completely reset syncing. In the Preferences, Lightroom CC Tab hit Delete All Data.