You simply need to remove three files from the project Path. navigate to Your Project Folder then permanently delete (“SHIFT + DEL”)
the files to permanently delete are: (‘File’ .gitignore ,’File’ .gitattributes , and ‘folder’.git)
(may be hidden so ensure you have your folders and search options > View > show hidden files, folder, and drives(Radio Button) Selected)…reopen VS and their is no more relationship to the Git Source Control. if you wanted to take it as far as removing it from the registry as mentioned above you could but shouldn’t be necessary aside from the “house keeping” of your machine. hope this helps.