If you navigate to the security role within the solution (on the dev side) there's an option to control the managed properties of components, which includes security roles.
This can be found by:
• Navigating to Settings > Solutions (and opening the solution in question containing the custom security role created) > Security Roles
• Selecting the custom security role from the main view
• Clicking on Manager Properties on the menu above the main view
• Setting the option customisable (or similar) to False.
This should prevent unauthorised changes being made on the live system.