I had a similar problem in which the install shield update manager kept trying to run agent (about every 2 minutes) to check to see if there was an update. The update manager sneakily installed itself like an opt-in for a mail list.
This began to get annoying with my noisy personal firewall warnings about update manager checks. Like you, I also could not find Install Shield in my Control Panel > Add or Remove Programs area, but I did find it under C:\Program Files\Common Files\InstallShield\UpdateService.
After doing a CTL-ALT-DEL to open the Task Manager, I stopped the Install Shield update manager and agent from running. Then I deleted those executibles in the Install Shield file. This may break something later, but seems to be working for now.