Hide user fields based off capability

This filter needs to return something. Try this

function modify_contact_methods($profile_fields) {
    if(current_user_can('edit_users')) {
        // Field addition and removal will be done here
        // Add new fields
        $profile_fields['company_name'] = 'Company Name';
        $profile_fields['company_id'] = 'Company ID';
    }

    return $profile_fields;
}
add_filter('user_contactmethods', 'modify_contact_methods');