There is probably an easier way to do this. I accidentally tried to add a large directory to a svn repo. It failed after 3 hours leaving half my directory with .svn folders. Since Tortoise SVN didn't seem to have an option to unbind a folder I wrote this powershell script.
function removesvn
{
dir -path $pwd.Path -recurse -force | where{ $_.Name -eq ".svn"} | rm -recurse -force
}
removesvn
