Can't sign PDF with new name

I am trying to get a client to e-sign a doc, but the problem seems to be that the client is using the same generic email address as the person who was at the company before them. The system is associating that email address with the old user name instead of the new one. Is there a way that my client can change it to her name in order to sign?  

Also, the signer does not have an account. I send the signer the document and the signer simply clicks on the link in the email they receive, signs the document and sends it back.