Deleting Snapshots 
Prerequisites
You are logged on to the database as the database system administrator or as a DBM operator.
More information: Glossary, Server Permission
The database is in the ONLINE or ADMIN operational state.
Procedure
In the context menu of the database, choose Administration.
Open the Snapshots tab page.
Select the snapshot you want to revert the database to.
Choose Delete...
More Information
Database Administration, Making Snapshots of the Data Area