Need to delete message in iRedmail

==== Required information ====
- iRedMail version: latest version
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  Mysql
- Linux/BSD distribution name and version: Ubuntu 12.04
- Related log if you're reporting an issue:
====

I need to know how I be able to delete messages from the server while using mysql backend for iredmail?