cubecolour

WordPress 4.5 added the ability to login using the registered user’s email address in place of the username. When this plugin is active, the ability to login using the email address in place of the username is removed, and the label of the input field is changed to reflect this.

No Login by Email Address

Removes the ability to login using the email address instead of the username.

wpyb

To prevent that usernames are publically visible, the username in the author’s permalink is replaced with the author’s ID. 
In case the page is invoked with the default permalink structure, it is displayed “Page not found”.
Additionally it is possible to modify the author base. It is recommended to make use of this plugin to change it, but it also works with other plugins that have the functionality to customize the author base.

Change Author Link Structure

To prevent that usernames are publically visible, the username in the author's permalink is replaced with the author's ID.

No Login by Email Address vs Change Author Link Structure