From within the Snapshots window there is an option to restore a snapshot.

All data entered after the date listed in the Snapshots window will be lost if a Snapshot is restored.

To restore a database to a prior snapshot, select the Manage Snapshots icon on the project ribbon. You will then be presented with the Snapshots window.

Only users with project manager rights have sufficient access to take snapshots along with System Administrators.

From within this window, select which snapshot you wish to restore, select the restore option, and confirm that you wish to restore the snapshot. The project will then be restored to the condition it was in when the snapshot was taken.