To remove a submodule you need to:
- Delete the relevant section from the .gitmodules file.
- Stage the .gitmodules changes git add .gitmodules
- Delete the relevant section from .git/config.
- Run git rm --cached path_to_submodule (no trailing slash).
- Run rm -rf .git/modules/path_to_submodule (no trailing slash).
- Commit git commit -m "Removed submodule "
- Delete the now untracked submodule files rm -rf path_to_submodule
https://stackoverflow.com/questions/1260748/how-do-i-remove-a-submodule/21211232#21211232 :