This article explains how to edit a recipient's email address when sending messages, and how to edit email contacts in Gmail. Instructions apply to the web version of Gmail in all web browsers.
How to Change Your Gmail Display Name | Change Your Sender Name in Gmail
Since most people have multiple email addresses (one for work and one for personal use, for example), Gmail probably has more than one saved for many of your contacts. As a result, Gmail may automatically fill in the To, CC, or BCC fields with the wrong input when you start typing the name of your email recipient.
However, Gmail makes it easy to edit this information directly from the New Message window:
Double-click the recipient whose address or name you want to edit.
