Johan van der Wijk

This plugin disables all WordPress updates (core, plugins and themes). This can be useful if you have multiple environments such as a live and staging server and you don’t want your users to use the update functionality.
This plugin not only disables the update mechanism for the core, plugins and themes, but it also removes the update menu item from the left navigation menu in the admin dashboard.

Disable Updates for WordPress Core, Plugins and Themes

Disables the WordPress update checking and notification system for all core, plugin and theme updates.

Sakthivel S

This plugin is used disable the wordpress functionality of updating core, themes & plugins automatically. Also it will disable all kind of update notification from wordpress.org theme/plugin repository.
Features 
* Disable WordPress core, themes, plugin update 
* Disable notifications for all updates available.

Disable All Updates & Notifications

Disable Wordpress, Themes & Plugins Updates along with their update notifications.

Disable Updates for WordPress Core, Plugins and Themes vs Disable All Updates & Notifications