I have PM7,just looked in my Add/Remove list and it is listed as Powerquest Partition Magic 7, maybe it is listed under Powerquest on your machine.
If not, look under Start/programs/partition magic and see if there is an uninstall option.
If not, all I can suggest is reinstalling, then look for uninstall options as listed above. Sometimes reinstalling can sort this out, I've had to do it many times. Hope this helps.