There is no seperate troubleshooting option for the PTR just follow the steps normally in the troubleshoot guide. The link offers either a better explanation or one that is likely to be identical to what you would get from a forum post.
You don’t need to do anything with your WoW folders just the Battle.net desktop app. If you don’t have a shortcut on your desktop it’ll be in your primary drive under an address similar to
C:\Program Files (x86)\Blizzard App