How to Remove a Field from a Form
Here is a code snippet that provides a general guide to removing fields from forms. See https://github.com/Charitable/library/blob/master/general/remove-form-fields.php
It lists the ‘hooks’ you should use for each form, as well as all of the fields that are included in those forms.
See https://github.com/Charitable/library#how-to-use-the-code-snippets for details on how to add a code snippet to your site.
Let us know if you need a hand adapting that.