You can clear individual notifications from the lock screen and Notification Center by swiping on a notification. From the lock screen, clear all notifications on screen by swiping down in the notification list to show a slideable Clear All option.
Add a reminder to a notification to re-alert you of it after the time you set. Show the reminder options by tapping and holding on a notification from the lock screen, Notification Center, or even on notification banners. Remove a reminder by tapping and holding on a notification in the lock screen or Notification Center to show a Clear Reminder option.
From the Messages application, you can add a reminder to a message by tapping and holding on a message from the other person in the conversation.
You can purchase Abstergo from the Cydia Store for $1.99.