Learn how to edit the posts that other users in your account created.
If you are the main account holder, you still have to add yourself as a user in your account and set the Admin role. Please check this article.
How can I approve posts of other users in my account?
When you log in using the username of that Admin, you should be able to edit the messages in the Queue tab of a sub-user.
However, we recommend that you use instead of the approval workflow so queue posts don’t go out before you’ve checked them and approved.