Don't allow to change User Name

How? Where?  I don't want users being able to change their user name; once they choose a user name and become known by that name I don't want them having the power to change it.

administration/fields.php   //edit profile then remove nickname from the list

 I did that and it did not change, user name was still in the edit list.  Is nickname different from user name?

clear caches and everything.  I drag nickname to the inactive block.  In the backend I am in profile fields, edit profile.  In the page builder you just have one block there.  This is the edit profile that you click on from your profile page.

That should work. Do you have "owner" checked and not "admin"?

[SMACKS HEAD]  I need to stop working when I am half-asleep.  It has been a job getting the new dedicated server set up and there are still things to do.  I keep forgetting about the admin view.  Now I feel right foolish  out here in the open and all LOL.  Oh well, it helps others as well I suppose.