We can show you how to fix that problem by using a plugin called Username Changer.
When you go to edit a user, the username is greyed out and there’s a “Usernames cannot be changed” message beside it.
- Go to Plugins > Add New
- Search for Username Changer
- Click on Install Now
- Click Activate Plugin
- Go to Users / All Users
- Select the User you wish to edit (I chose testuser)
- Click Edit (text link underneath the username)
- Click Change Username
- Type the new username (testuser2)
- Click Save Username
You can double check the name change by going back into Users / All Users. You will find the new username in your list. (See image below).
Finally, If you won’t be using the plugin regularly go ahead and uninstall it. That way, just in case there were to be security issue with it, your site won’t be affected.
That’s all there is to it. You’re done. Congrats!