If you need to stop receiving new user email notifications in WordPress, install and activate the Disable New User Notification Emails plugin.
Upon activation, the plugin simply disables new user notification emails in WordPress. It works out of the box, and there are no settings for you to configure.
Note that this plugin does not affect any other emails sent by WordPress. For example, users registering on your site will still get their username and password in the email. They can also recover their accounts if they forget their usernames or passwords.
The plugin only disables new user notification emails sent to the admin email address on your WordPress site.