I started working on a project 2 years ago and I chose SVN as the revision control system. Then in last year I decided to switch from SVN to GIT via git svn clone. From then on, I never commit to old SVN repo again. I'm the only one using the repo so there is no branchs in both SVN and GIT.
Now I want to remove the git-svn tag here: (I'm not sure if it is a tag.)

All the commits and logs in old SVN repo must be retained.
What should I do? I'm using TortoiseGit and knows just a little about git commands.
