Trying to modify the Job submission page

Hi,

I am founding a problem modifying the job submission front page.
I just want to remove the company_twitter field and the header image.

I am trying to use the remove_action function.

So my code looks like this

<?php remove_action(‘submit_job_form_fields’, ‘company_twitter’, 20); ?>

and I add this to function.php of my child theme. But I see no changes. What am I doing wrong?