How to delete git submodule

My blog use hugo framework, and install theme by using git submodule.

Each time I change my theme, I want to completely remove submodule of old themes.

Solution

• Open .gitmodules files, remove relevant section.
• Stage the .gitmodules changes: git add .gitmodules
• Open .git/config, remote relevant section.
• Run git rm --cached path_to_submodule
• Run rm -rf .git/modules/path_to_submodule
• Commit git commit -m "Removed submodule"
• Delete the submodule: rm -rf path_to_submodule

Reference: https://gist.github.com/myusuf3/7f645819ded92bda6677