Full Use Case:
I am using email feature with A5 Documents and want to be able send generated document as PDF attached in email though don’t want to store the PDF on Salesforce record as this will use up my storage. Rather than manually deleting attachments from records, is there an automated job to setup an auto or mass delete?

Consulting Reply: 
To to set up the job you would write and APEX class that could query for attachments that are related to email/task records and any other logic to filter attachments you want such as an email subject. Then delete them. And schedule APEX class to run once a day for example. If you would like our consulting team to configure this process for you, contact support.

Another workaround to avoid attachments in Salesforce would be to send the generated document as a link to google doc within email (which end user can then export to a PDF format if needed). That way you are not using attachments at all and don’t need to worry about deleting them.