you didn't follow the rest of the steps which are to inspect the form element you don't want to have appear in the email, it looks like in the case the name is:
Hidden_Field
and
SimpleContact_submit
and then to edit the line that was a added:
$remove[] = "y";
and replace y with the form field name, in you case, you have 2 form files, so you need to do this twice:
$remove[] = "Hidden_Field";
$remove[] = "SimpleContact_submit";