The problem with that could be that if Steam's uninstaller doesn't get rid of config files you could do that reinstall and have the same error.
If I remember correctly, Spy Bot Search and Destroy has a function where it will find any and all duplicate files (yes, ALL files) on your hard drive(s). Unless you want to go in manually to the TS folder and search for the one stupid file causing this, and depending on how large your Ts install is, you could try the Spy Bot thing. It's a free download and altho it could take a while (hour maybe?) it might save time from a reinstall.
I just did reinstall TS2020 all 56Gb of it and it was an all nighter. Just to get the TS2021 upgrade to work. I feel for 'ya.