Download a built release of Clang/LLVM version 13.0.1 from GitHub and put it into third_party/clang+llvm-13.0.1
After this, you should find:
ls third_party/clang+llvm-13.0.1/
yields:
bin include lib libexec share
Then:
mkdir build
cd build
cmake -G Ninja ..
ninja
Then you can do:
./remove-parens /path/to/source/file --
If your source file will include standard headers, then you will need to copy the remove-parens executable into:
third_party/clang+llvm-13.0.1/bin/
and run it from there.