Completely remove git repository binding or mapping of a project,and then commit it on git as a new one?

Basically all the information of a git repository in a project is stored in .git folder in that project's root directory, so for removing git binding/mapping or tracking you need to remove that folder and you can add it as new project on git repository, for the purpose you can follow the steps:
1)Go to the root directory of your project and make .git folder visible it is a hidden folder by default.(for windows, open your project folder in file explorer -->view-->Hidden items, enable this check)
2)Open your project's root folder in command prompt and run following three commands where first one will remove everything inside .git folder, second line will remove the .git empty directory and third one will initiate fresh instance.

del /F /S /Q /A .git
rmdir .git
git init

Then you can create a fresh clone of your empty git repository and merge your project to that one.