While CRM default view limited the customization of the view, you will see those view showing "You cannot delete this view". I will show some simple trick in order to Enable it back (You can delete system view then :D )
The CRM view setting actually store inside the database table [savedquerybaseset ]
Column [IsCustomizable]: * default is 0, just update it to 1.
Column [IsPrivate] to value 1 to hide.
update savedquerybaseset IsCustomizable=1 where name like 'test delete%'
If you having problem to remove column from view, refer to KB below:
Error message when you customize a view
Simple add about:blank to Trusted Sites.