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.

geenenitsysteme

Simply disables all update notification emails (core, themes, plugins). No configuration needed.

Disable All Update Notifications

Simply disables all update notification emails (core, themes, plugins). No configuration needed.

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