The developers at cPanel removed the aging option in the latest version. However, you actually don’t need to have the email address setup in Mail > Add/Remove/Manage Accounts.
For example, let’s say you want any emails that goes to email@example.com to forward to firstname.lastname@example.org. You don’t have to set up email@example.com in Mail > Add/Remove/Manage Accounts.
Just go into cPanel > Mail > Forwarders > Add Forwarder.
In the first box you would enter ‘sales’ and then you would select the correct domain (if you have more than one domain set up). In the second box you enter firstname.lastname@example.org.
Now, when someone emails email@example.com, the email will be forwarded to firstname.lastname@example.org. This way, nothing will be sitting on the server taking up space and you won’t have to worry about cleaning up old emails.