Hi,
Do you want to hide the reminders or meetings?
If you need to hide the specific meetings, we need to create a View filter in Outlook calendar. However, there is no direct way to create the filter to hide the meetings older than a specified amount of time. If you know SQL, you can create the criteria
directly in: View -> Current View -> View Settings -> Filter -> SQL -> Tick "Edit these criteria directly. All other tabs will be unavailable", enter the criteria in the blank box:

I'm not familiar with the SQL syntax, but if you can let me know what the amount of time is, I will try to do a little research on it.
Regards,
Melon Chen
TechNet Community Su