Deactivating system views from a managed solution

Hi All,

I have a managed solution on CRM 2016 and there system views which we want to remove / deactivate. Also, the customer wants to make customizations to forms which it does allow you but when it comes to migrating the solution onto a new CRM platform which I am planning on doing soon, what is the best way to achieve this and make sure everything is linked to the package?

Thanks,