if tenons iTools has an uninstaller, then by all means, use it. apache is the default web server for OSX, and it is a very robust, very secure web server, so it is a great thing to have. it is also free.
i m not sure if tenon s iTools is just a frontend to apache, or if it is a different web server. i don t have Tenon iTools, so i can t troubleshoot it. but iTools is not free, so since you paid for it, it would be ashame not to use it. perhaps your money that you paid entitled you to tech support, so perhaps you should call Tenon and ask them for help.
if you don t want to do that, then uninstall iTools. i hope that if you uninstall iTools, it will restore your system to the way it was. but right now, just deleting iTools will break your system. right now, apachectl is turning on tenon iTools, so if you just delete Tenon, then apachectl will just fail, not finding what it is looking for.
if that happens, then your options include reinstalling apache (you might consider upgrading to versoin 2.0), or reinstalling the OS. if you reinstall the OS, then you are guaranteed that everything will be in mint condition, and that the web sharing preference pane will once again be able to control your apache web server. i would hope that the Tenon uninstaller (if there is one) would also be able to restore the system to the original functionality, but i really have no idea. uninstallers are a little bit uncommon in the mac world.
so do you have an uninstaller? if so, then use it, and tell us if anything works.