WP_User::remove_role()
Method: Removes role from user.
Source: wp-includes/class-wp-user.php:574
WP_User::init()
Method: Sets up object properties, including capabilities.
Source: wp-includes/class-wp-user.php:172
remove_user_role
Action Hook: Fires immediately after a role as been removed from a user.
Source: wp-includes/class-wp-user.php:592