`What you have done is incorrect and needs to be corrected to avoid issues in reporting scores. You should have only one account with ACT. As to ACT and reporting scores to colleges;
With ACT, every order to send scores to colleges is an order to send a single test. If you have multiple tests, you have to do multiple test orders. In other words, there is no score choice or lack of score choice with ACT because it is only going to send the particular test you order sent. Other than for the test you order sent, and contrary to what is mentioned above, ACT does not provide anything to colleges to even hint that you took other tests. Note, that is actually the same for SAT. College Board will send all your scores in one order but you can exclude one or more prior tests when doing the order. CB, like ACT, provides nothing to colleges to indicate that you have tests that have been withheld.
Unlike SAT, ACT has a process (you need to contact ACT to begin the process and get the initial form) to cancel scores after they are released. It takes some time, so you would need to start immediately if you want it done by fall. Once removed, ACT eliminates its record of your test, i.e., a college could not find it even if it hacked into ACT’s systems and tried to find the information.
There are a small number of colleges that require you to provide all your ACT scores: Stanford, Penn, Carnegie Mellon, Yale, Harvey Mudd, Georgetown, Cornell, Barnard, and University of Miami. If you are not applying to one of those then you can submit whatever ACT tests you want to submit. And those do not require an ACT test that has been canceled (for which no official record will even exist at ACT if canceled). As to your setting up a separate account with ACT, that does nothing to change the rule that you are supposed to provide all ACT tests to those colleges. If you are going to withhold a score, you can just do it even if you have one account so having two does not add anything.
If you are trying to withhold a score from a college, ACT and College Board are not the problem as you can easily do it with them. Your real adversary may be your own high school. When you apply to college, you will need for most colleges to submit an offical high school transcript as part of your application. There are many high schools that put all your test scores on your transcript. In other words, you better check with your high school what it has and what it puts on the transcript sent to colleges. If it has last year’s score (likely), and it puts scores on your transcript then your effrot to hide scores with ACT may result in utter failure except to prove to a college that you tried to withhold a score when it gets no applicable score report from ACT but gets your transcript with the score. Note, if you cancel an ACT score with ACT, it will send notice to hthe high school that the score has been canceled and is no longer valid. High schools that put scores on your transcript will typically remove them if there has been a cancellation but you have to make sure that gets done.
Finally, consider whether it is necessary to hide anything. Even the colleges that require all ACT test scores assert that they do not hold the lower scorers against you and use the highest scores to determine admission.