Below it the link to Microsoft support, it goes over setting a policy restricting users to certain folders in the start menu using the registry. I haven’t found anything easier that would give you the same outcome.
Editing the registry is not actually the best solution for your start menu problems. The best thing you have to do is to pin the start menu content or remove in manually. It is because editing the registry my create an additional problem related to the system, remember that registry composes of many sensitive system files.