First, you need to ensure the module ‘menu_setup’ is assigned to the tenant.
Then you can customize the tenant admin menu can be done by sharing and enforcing ‘aside menu active’ and ‘setup menu active’ in the package shared settings. However, this might require you using similar menu with tenant if you still use the master CRM for seeding tenants.
If you have dedicated instance for seeding, login into the instance and configure the menu.
You can prevent customer from seing the ‘menu setup’ link by excluding it from the Main Menu setup. However, you need to note the direct URL to the module page i.e /menu_setup/main_menu or menu_setup/setup_menu for direct access.