As an administrator, you can enable and disable object definitions for specific roles. This way, all users of that role will see only the object definition you set up for them.
You can manage the existing object definitions via 'Roles' in the access and identity section of the admin portal. When selecting a role, you will see this option:
When creating a new object definition, you can select which roles should see this in their personal settings.
Note: If a user still wants to enable or disable personal settings, then this is possible. The personal settings that are set by a user will overrule the settings that were set by the admin. If a user has never changed their personal settings before, the admin settings will be their baseline.