At the moment, there is no way to customize email subscription settings. The only option is a hard-coded 'Unsubscribe' button.

Instead, it would be much more helpful to have an 'Unsubscribe' button that then takes you to a screen where you can have some options about what you want to unsubscribe from. "I want to receive fewer emails." "I don't want to receive solicitations." "I only want to receive newsletters." "Unsubscribe from all communications."