You can change the email address of your signer after sending out a case file by following this guide.
After you change the email address, the new recipient will receive a new email with a new signing link at the updated email address, granting them access to the document. The original email address will no longer be linked to the request, which means that the previous recipient will still be able to see the email they received from Penneo, but their signing link will no longer be valid.
Attention: it's possible that the person who is linked to the wrong email address has clicked on the signing link (and downloaded the documents) before the sender of the case file changed the email address of the signer. You can check whether the wrong signer has clicked on the signing link in the event log of that signer.