How do I uninstall TortoiseSVN?

Simply uninstall from Add/Remove Programs in the Windows control panel. This does not effect your repositories or working copies at all. Be aware however, that the subversion database schema might change before subversion 1.0 is released.
When you are working with local repositories (file:/// URLs), a newer version of TortoiseSVN might be incompatible to an old repository. Please check the subversion release notes.