How to remove "Report URL" from emailed PDF reports header?
It seems to be hardcoded (https://github.com/civicrm/civicrm-core/blob/master/CRM/Report/Form.php#L3405), but you could use hook_civicrm_alterMailParams and do something like (untested - you might have to adjust the regex):


if ($params['groupName'] == 'Report Email Sender') {
  $params['html'] = preg_replace('/^Report URL.*$/', '', $params['html']);
}


Another option which is maybe simpler is just completely replace the html in the hook, if you don't really need the other text either:


if ($params['groupName'] == 'Report Email Sender') {
  $params['html'] = 'Insert your own html';
}