If you no longer wish to use Corel X5, the correct way to remove Protexis is to uninstall the Corel software itself.
The following guide outlines how to manually disable the service or use the RemoveProtexis.cmd script method to clean up your system. What is Protexis-cmd and the Licensing Service? Corel X5 Remove Protexis-cmd
Uninstall via Programs and Features (preferred) If you no longer wish to use Corel