Were these regular emails (sent to a list of contacts) or automated emails (used in workflows)?
Once a regular email is sent, editing isn’t possible anymore. Editing this email would be pointless, too, since it was already delivered to the inboxes of your recipients. If you want to send another improved version of this email to more contacts however, you could clone it, as explained here: Clone HubSpot content After cloning, you will be taken to the email editor.
It is not possible to edit Regular emails, once they are being sent. However Automated emails can be editied anytime:
To edit Automated email: Edit Automated Marketing Email | Loom
Hope this helps!
To create an improved version of you mail, i will advise you to clone the email and then edit it:
To clone and edit an email: Cloning and editing a marketing email | Loom