Notifications eventually lose their relevance; who cares if a supervisor was notified about a cancelled assignment from two years ago? VSys lets you archive old notifications to a file and remove them from the system. In the future, if you find that you need those notifications back again (e.g. for an audit), you can de-archive the notifications to bring them back into the system.
From the Notifications subscriptions tool, click on Archive notifications. Select a date range of notifications to be archived, select a File and click Run. (To have VSys actually remove the notifications from its database, check Remove notifications... first.)
Don't remove recent notifications. VSys takes care to not send out duplicate notifications about the same event. If the previous notification for an event is not there, VSys may send out a new notification.
From the Notifications subscriptions tool, click on De-archive notifications, then the name of the archive file. You can limit the date range for notifications brought back in, then Run. If the archive file contains notifications that are already in VSys, VSys won't overwrite the existing notification, so when it tells you how many notifications were restored, that number could be less than the number you expect, even zero.