Menu itself just will not go away

This is NOT like other menu ‘can’t delete item’ posts.

Whilst experimenting with Menus I went to Appearance > Menus and created a ‘testmenu’, I used the following code in my theme:

<?php wp_nav_menu( array( 'theme_location' => 'testmenu' ) ); ?>

Super, all working fine. The trouble is I’ve now created a new menu that isn’t just test data. It’s called ‘Top Header’

<?php wp_nav_menu( array( 'theme_location' => 'Top Header' ) ); ?> but ‘testmenu’ appears. So I try:

<?php wp_nav_menu( array( 'theme_location' => 'top-header' ) ); ?> but still ‘testmenu’ appears.

So I go back to Appearance > Menus and delete the menu ‘testmeu’ I go back to my browser, refresh the page and ‘testmenu’ appears. I go to another computer using a different browser and ‘testmenu’ appears.

I change the code in my theme to:

<?php wp_nav_menu( array( 'theme_location' => 'zxxddfedefre' ) ); ?> and you guessed it ‘testmenu’ appears!!!

How the heck can I get rid of ‘testmenu’ and have my new menu’s that I actually want appear?

I want ‘testmenu’ dead, gone, killed. It’s like the terminator – it just WILL NOT go away!!

Please help!