If you need to cancel several upcoming sessions, you don't have to remove them one at a time. As long as they belong to the same activity type, you can remove them together.
Removing several sessions at once
Go to Play → Activities → Types.
Click on the activity type and open the Upcoming tab.
Checkmark the future dates you want to cancel.
Click on Action and remove all the checkmarked dates in one go.
Good to know
Only empty sessions can be removed this way. If a session already has players on it, it has to be removed from the regular schedule view instead.
You can only remove sessions in bulk within one activity type at a time.