You seem to want to change the SVN respository that you're pointing to. There is another Question And Answer, but it seems pretty ugly.
Having installed the latest version of ankhSVN on Visual Studio 2013, it seems pretty trivial to relocate to a different SVN respository.
Right click on the Solution -> Subversion -> Switch Solution
On the menu, you should have an entry pointing to the current location of the solution. If the repository is the same, but under a different URL e.g. changing hostname, directory, etc, then simply change the relevant pieces in the URL and hit enter.
It will prompt you that the root you've specified is different from the one that you're currently using and you can simply relocate it from one to the other - i.e. choose to relocate. It will then prompt you a second time to switch, but this should be a free change.
If the new repository is different to the old one i.e. it's somewhere completely different in a different repository with a different repository ID then you're going to have to do some form of manual changing by following the instructions on the other answer.
If you want to remove the svn metadata for the project, it's in a single directory called .svn at the root of the solution that was checked out from subversion, as well as removing the information in the .sln
file that mentions AnkhSVN
(it's probably the only entries mentioned in a specific GlobalSection in the file mentioning source control). That purges all the svn data from the solution.