Taking update notification off?

Hey everyone,

I’m pretty sure this would be simple but i can’t find the relevant php file to edit. All i want to do is take off the notification – ‘A new version of WordPress is available! Please update now.’ off from the admin pages….i’m about to show a client how to edit his pages and i’m thinking that this will confuse him. (I am using plugins that don’t work with the new wordpress thats why i’m not just updating)

thanks!