Not that hard really, but lost some time with this because I tried to do this in the Original folder where the Original TFS was pointing to.
So, you can unbind your solution on any location, but once you've done this, copy your solution to another location so you can bind it with a different Team foundation system.
You can simply undind by going to File, Source Control , Advanced, change source control.
If this doens't work you can also use a tool for it.
at this current time, you will have to rebuild it because the regex in the code isn't correct. Just look at this post: