ProcessWire: Remove field via API

fieldRemove.php

<?php
if ($user->isSuperuser()) {
 
    //first remove the fields from 'user' template before deleting them.
    $t = $templates->get('user');
    $fg = $t->fieldgroup;
    $fg->remove($fields->get('your_field'));
    $fg->save();
 
    //delete the fields
    $f = $fields->get('your_field');
    $fields->delete($f);
 
}