Your team will always have the option to cancel or reschedule meetings, but if you want attendees to be limited to a window of time, this technique will help. They will only be able to cancel or reschedule based on your rules.
Begin by navigating to the Pages screen and click on the meeting type that you want to edit.
Once your meeting type editor is open, navigate to Scheduling Rules in the left navigation menu and scroll to the bottom of the page. You'll find the option to Allow Cancellations or Allow Rescheduling, which you can switch on or off.
If an attendee attempts to cancel or reschedule a meeting outside the allowable time frame, they will be blocked and cannot proceed beyond the error screen shown below.