Add in Users Table from Wordpress Dashboard a new sortable column with user_registered datum (Register Date).

Add WP Users Table Register Sortable Column

<?php
function alisios_add_user_column_registered( $columns ) {
    $columns[ 'user_registered' ] = 'Register Date';
    return $columns;
}
add_filter( 'manage_users_columns', 'alisios_add_user_column_registered' );

function alisios_add_user_sortable_column_registered( $columns ) {
    $columns[ 'user_registered' ] = 'user_registered';
    return $columns;
}
add_filter( 'manage_users_sortable_columns', 'alisios_add_user_sortable_column_registered' );

function alisios_show_user_column_registered($value, $column_name, $user_id) {
    $user_data = get_userdata( $user_id );
    if ( 'user_registered' == $column_name )
        return $user_data->user_registered;
    return $value;
}
add_action('manage_users_custom_column',  'alisios_show_user_column_registered', 10, 3);