Hi James,
Depending on the time of license held, there are various ways of getting this sorted.
The easiest way is to simply change the email address of the Salesperson to another email address. To do so, the user simply logs into their Adobe Sign Account > My Profile > Click on 'change email address.' A request can also be put through to the Adobe Sign Support team via email. You may require email permission of the Salesperson to do so, or if this is no longer possible as he/she's already left - you may have to answer a few questions for Privacy & Security.
I've dropped you an email with the Adobe Sign Support details to create a ticket to change the email address.
Alternatively, please note that with the Adobe Sign Enterprise license you can download agreements in bulk using the Bulk Download Tool. You can choose to only download all the agreements for a specific user to save anywhere else.
Hope this helps!
Kind regards,