feature request: turning off notifications of calendar app

feature request for turning off the notifications on the calendar app. i use a 2nd calendar app that i like better, but now i continuously get 2 notifications. I have tried:

• in the calendar app settings there is no option to turn them off (only to make them silent)
• i have tried the little gears icon in the notification bar (but there it says notifications for this app cannot be turned off)
• Settings/apps/ – calender app -- Notifications. Here the option to disable the notifications is greyed out. So notifications are still occurring twice on my phone :). Rik

screenshot for the 3rd thing i tried, where the options are greyed out: