Hi Jason,
Do you mean you open one URL with extension .ics by Outlook client?
If yes, as far as I know, we are able to delete this calendar in your Outlook client if we don’t want to view this calendar. You can refer to the steps below:
Go to Calendar < Other Calendars < Delete Calendar.
If you want to do this in OWA, from what I understand, the OWA is not able to add the calendar with the extension .ics.
If you complete the steps above and the issue persists. Can you provide the following information:
1.Where are you get this link with the extension .ics?
2.Can you provide the detailed steps and some screenshots about how to add this calendar to your calendar?
To upload screenshots, select Use rich formatting, and then click insert /Edit
Thanks,
Toby