If you no longer wish to receive notifications of updates to your WordPress administration, a few lines of code in this tutorial will be sufficient to hide them. Updates of the core, themes and plugins will no longer appear!

Note: These tips only work for WordPress 3.0 onwards. We have not checked for WP 3.5 upwards.
Hide update notification from the core of WordPress
Log into your WordPress admin, then scroll down and click the Editor (under Appearance).
Then open the functions.php file from the list on the right.
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In the end or beginning of file – including the theme TwentyTen, add the following lines of code:
add_filter ('pre_site_transient_update_core' create_function ('$ a', "return null;"));
Hide update notification of WordPress Themes
The procedure is identical. Reopen the functions.php file and paste these lines of code:
remove_action ('load-update-core.php', 'wp_update_themes');add_filter ('pre_site_transient_update_themes' create_function ('$ a', "return null;"));
Hide update notification of WordPress plugins
Again, just paste these lines in the functions.php file:
remove_action ('load-update-core.php', 'wp_update_plugins');add_filter ('pre_site_transient_update_plugins' create_function ('$ a', "return null;"));
Remember to Update the file.
WordPress is now configured to hide all notifications of updates.
Note : Please take backup of these files before any editing. We have not tested for current version of WP, From comments its verified they work fine up to 3.3.x. Your feedback is valuable.

thanks! its very useful for my wordpress blog ;)
this doesnt work with wp 3.2.1 …all it is here is rubbish
Which Theme / Theme Framework you are using?
Wow thanks.. i was looking for a plugin which help me to disable notification i donnow it will work with wordpress 3.3.1 let me try this
Thanks
**Before you make edits, backup functions.php
I integrated this into theme folder functions.php file – zero luck :-/
Unmodified functions.php file will be in the Theme’s package.
It depends on the Theme / Theme framework. Kindly ask your Theme creator for function reference.
This did not work for 3.3.2 so dont waste your time.
Try these:
//plugin update notifications
remove_action( ‘load-update-core.php’, ‘wp_update_plugins’ );
add_filter( ‘pre_site_transient_update_plugins’, create_function( ‘$a’, “return null;” ) );
//core update notifications
add_filter( ‘pre_site_transient_update_core’, create_function ( ‘$a’, “return null;” ) );
Bleargh!! You’ve broken my whole site and now I can’t get it back! *sighhh* I hate being so code stupid.
You possibly added extra bit of codes or added a leading space. Codes will be like this :
If ?> already exists, you need not to add it, simply omit it. We have edited out from the main post above after watching that some visitors actually having the issue to understand the php closing part.
Basically a bit knowledge of php is required for editing. Anyway, to get back your broken site to working, simply delete the modified files and replace them from backup or from same version of wordpress package or theme.
After that, if you edit with new codes (we removed the ?> things), they should work. You can ask us for free help if you got stuck at any step.
You are missing a comma in add_filter function :-|
WP is removing it…