add account on device or in app?

[AC Question]

If I add an Microsoft Exchange ActiveSync account in Settings/Accounts both the email and the calendar app that shipps with the Samsung Galaxy S7 immediately becomes aware of this account. So is my favorite calendar app, DigiCal. Problem is I don't seem to be able to "disconect" this account from the Samsung S Calendar app, so I get double notifications. I also want to use a different email app than Samsungs, but I can't find any that connects to the account I created in the settings.
So, where is the best place to add an EAS account, once in the Settings/Accounts, or in the apps (emai, calendar and task apps)?

 

[Rukbat]

In the Play Store. Find an app that ONLY does exchange, (The only way to link 2 apps to the same email address and only get one notification is to turn off notifications in one app.)