如何删除Xcode 7项目上的所有本地和远程Git

I'm working on an iOS Xcode project whose previous developer has configured and committed to local git and remote git using his account. Now I want to delete every source control existing on the project (local and remote) and recreate a new one. How can I make everything fresh so that I can commit and use the source control? (I don't have the previous developer account.)I'm working on an iOS Xcode project whose previ