To uninstall Link Checker from your computer, you will need to shutdown Link Checker instance and follow one of the two way to uninstall Link Checker:
Going to Start -> Programs -> Link Checker Free Edition -> Uninstall Link Checker Free Edition and following the guides.
Going to Start -> Settings -> Control Panel. In the Control Panel window, double click Add/Remove Programs. Find and select Link Checker Free Edition, click Modify / Remove and following the guides.
Note: It's strongly recommended you backup your project files before the uninstallation.