Give to site admin the option to "skip confirmation email" when adding new user

Add the following to your funcitons.php file

    function skp_custom_user_create_fields($user){
    if (!is_super_admin( $user_id )) {
?>

    <table class="form-table">
        <tr>
            <th scope="row"><?php _e('Skip Confirmation Email') ?></th>
            <td><input type = "checkbox" name = "noconfirmation" value = "1" <?php checked( $_POST['noconfirmation'], 1 ); ?> /> Add the user without sending an email that requires their confirmation.</td>
        </tr>
    </table>
<?php
    }
}
add_action("user_new_form", "skp_custom_user_create_fields");

function skp_auto_activate_users($user, $user_email, $key, $meta){

    if(!current_user_can('manage_options'))
        return false;

    if (!empty($_POST['noconfirmation']) && $_POST['noconfirmation'] == 1) {
        wpmu_activate_signup($key);
          return false;
    }
}
add_filter('wpmu_signup_user_notification', 'skp_auto_activate_users', 10, 4);

That would do the job.

Paste this in your functions.php file:

function my_skip_confirmation_email() {
    if ( is_multisite() && current_user_can( 'create_users' ) ) { ?>

    <table class="form-table">
        <tr>
            <th scope="row"><?php _e( 'Skip Confirmation Email' ); ?></th>
            <td>
                <input type="checkbox" name="noconfirmation" id="noconfirmation" value="1" />
                <label for="noconfirmation"><?php _e( 'Add the user without sending an email that requires their confirmation.' ); ?></label>
            </td>
        </tr>
    </table>
    <?php }
}
add_action( 'user_new_form', 'my_skip_confirmation_email' );