How to remove a submodule (Excerpt from https://git.wiki.kernel.org/index.php/GitSubmoduleTutorial#Removal)
1. Delete the relevant line from the .gitmodules file. 2. Delete the relevant section from .git/config. 3. Run git rm --cached path_to_submodule (no trailing slash). 4. Commit the superproject. 5. Delete the now untracked submodule files.