You cannot delete the scanner profile until you add a new one. I suggest you reinstall the HP program and add the Canon Scanner profile. After you added the new profile, go to Scanner tab, select the HP profile from the Profiles window and press the Delete Selected Profile icon. If this doesn't work, uninstall Kofax Capio using Add or Remove Programs feature:
If you use Windows XP or bellow you can go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the Kofax Capio program and then click Remove.
If you have Windows Vista or above you need to go to Start > Control Panel > Programs > Programs and Features. Select the Kofax Capio application and click on Uninstall.
After that, try running AdwCleaner 2-3 times in a row to make sure that there are no leftover rogue registry keys or profiles information in your system and reinstall the Kofax Capio software.