Does taking only 1 subject test when I registered for 2 affect my chances?

I signed up for Biology M and Math II. I am ready for Math II, but I did not have enough time to prepare properly for bio, had some issues that really took time off of my studying schedule. I read that I can take only one subject test and then walk away and nothing happens. Is this true?
Also, will colleges be able to see in my test taking history that I registered for 2 ST and took only one on test day? If so, will it affect my chances of admission?

Colleges can only see the score reports you send them- for them, no score report=no test. So don’t worry, it will not affect you in any way if you decide not to take one subject.
I’m sure you can take only one, but I think you should let the proctor know beforehand. Not sure if you have to sign anything, but I would ask at the test center just to be sure.

Thank you very much! I’ll do that then.