If you need to uninstall ChimpRewriter before a major version upgrade or otherwise, you can simply uninstall through your control panel as you would install any other application.
Instructions for the major Windows versions below:
Windows 8: http://windows.microsoft.com/en-au/windows-8/free-up-disk-space#
Windows 7 or Vista: http://windows.microsoft.com/en-au/windows7/uninstall-or-change-a-program
Windows XP: http://support.microsoft.com/kb/307895