Removing Menu by Child Theme

HI,

I am trying to unregister the default menu that tungsten mounts but whenever i try <?php unregister_nav_menu( ‘primary’ ); ?> in the functions.php file the backend crashes, i know this is not the correct way based on how this theme is written but it appears that the theme is written in a slightly different way to the wordpress codex suggests.

Any help on this would be apprechiated, thanks!

PS: i am trying to remove the one menu so i can add two new ones, one in a similar place to the exisiting menu, and one at the very top of the page viewable to all (directly under the admin bar if the user was to be logged in).