Will ACT invalidate my scores if I do worse?

So back in October 2017, I took my ACT without writing and got a 33. I was satisfied with my score but once I started looking into college apps, I was made aware that some universities I plan on applying to “strongly recommend” taking the written portion of the ACT. I don’t want to risk them not using my ACT score since it was a lot better than my SAT, so I signed up to take the ACT with writing for this Saturday. The thing is, though, I haven’t studied for the ACT since October when I had a tutor. Right now my practice tests are putting me at around a 28. I know people get their scores cancelled for doing significantly better, but will mine be cancelled if I do significantly worse?
I called ACT about rescheduling and I really don’t want to pay the fee for it, but if I really need to I will. Please, if anyone. has heard of this happening let me know. I’m desperate at this point.

I have never seen someone report that a lower scoring ACT test was cancelled because it was too much lower than a previous score.

More and more universities are eliminating any requirement for the writing section (recent additions to that group include Stanford, Princeton, Harvard and Yale (there is no longer an ivy that requires the writing section). But as you mention some still recommend the writing. However, recommend does not mean they will not use the ACT w/o writing.

Personally I would not take it again in your situation unless you are actually applying to a university that requires writing or you firmly believe you can score high when taking it again because: (a) the writing score likely has not been a big factor in admission, a fact demonstrated by all the colleges that keep dropping it as a requirement; and (b) If you actually did a lot worse, causing ACT to raise a question about the valifdity of a test, you could face the ACT’s potential cancellation of the first test not the new one, i,e, its reaction would be to assume the high score is the false one.