There are different ways to disable WordPress updates. Below we will list how to disable updates manually in your site's wp-config.php file and with your functions.php file from your theme, as well as other plugin methods.
Disable WordPress core updates
To disable automatic WordPress core updates, add the following line to your wp-config.php:
define( 'WP_AUTO_UPDATE_CORE', false );
Disable theme & plugin updates
Add the following to your active theme's functions.php file to disable plugin updates:
add_filter( 'auto_update_plugin', '__return_false' );
To turn off updates for themes, use this filter:
add_filter( 'auto_update_theme', '__return_false' );
Disable WordPress updates with a plugin
An easy plugin to use in order to disable all WordPress updates for core, plugins and themes is Easy Updates Manager.
Another option is the plugin called Disable All WordPress Updates.