No, you don't have to report it, however, ALL attempts that you've made on the PCAT will be sent eventually whenever you do decide to send your scores.
For example, you get a 30 the first attempt but don't send it to any schools. The next attempt you get a 78 and send your score, the first score will be sent as well so schools will know how many times you've taken it. Essentially, no way to hide a bad attempt.