I did something no self-respecting developer should do and paying the price for it!
I ran a line count util in my project which created a bunch of files to show line count stats.
I then removed them manually from the folder. Now those files keep showing up in "Pending Changes" every time I try to check my code into my VSTS repository -- see below. But those files are not there at all.
How do I remove those non-existing files so they don't show under "Pending Changes" anymore?