How to disable "unable to sync calendar" Gmail alert

[AC Question]

I have a Nexus 6P. This "unable to sync calendar" Gmail alert occurs 1-2 times a day. I'm pretty sure it's coming from my work exchange email account. I don't want my phone calendar to have work items on it, just to be a personal calendar. I've set various things to off in my phone settings, calendar settings, and Gmail settings -- still occurs every day. So I'm wondering if anyone else experiences this and/or knows the solution.