How to remove folder properly from git repo

Step 1: Add required_folder_path/ to .gitignore file
Step 2:
$ git rm -r --cached required_folder_path/
or
$ git rm -r --cached .

sometime if warning occurs this command will not be completed for that use '--ignore-unmatch' option.

Therefore the it should be:
$ git rm -r --cached --ignore-unmatch required_folder_name/
Step 3: $ git add .
Step 4: $ git push

To undo
$ git rm --cached filename
$ git add filename