Cannot delete a custom field (option set) from a custom entity.

I am trying to delete a custom field from an entity it shows it has dependencies to two custom vies and a system view. I have removed the field from all views and published the solution and it still appears as the dependency relationship exist. In order to remove it from the custom views, I deleted the sub-grids on forms the entity existed and had to delete the view. Unfortunately, I cannot do the same for the system view.

Microsoft Dynamics CRM 2015