How can I turn off Calendar text reminder

I keep receiving Calendar "text" reminders, in addition to Notification Reminders. It's ANNOYING because I already choose which events I want a notification for, within the New Event "form" each-time I create a new event. I can choose to be alerted 5min, 1hr, 2days before the Event ...or I can choose "none"....... However, even if I choose "none" I keep getting incoming text reminders to my text messages, in addition to a screen Notification (which I prefer). No matter what, I will get a text reminder. I put on my calendar; Tuesday 28th/4pm/Portland trip/no alerts... just so I know not to schedule anything else that day, not because I need a remindeder. So it obeys me and doest send the Notification pop-up, but while I'm driving to Portland an incoming text comes in at 4pm to remind me OF WHAT I'M ALREADY DOING. How can I make these dual reminders stop? I will gladly choose one or the other....either a Text or a Screen Notification. Any help you can offer would be great. Thank you!