Can I change my test option ?

I have registered for the ACT with writing on October 22 but now I want to change it to ACT no writing. However, I am now out of the registration period and cannot make a change of test option. I’ve read the instruction on act.org and it says it’s possible to change test option on the day of the test if there are enough rooms, materials,…but who knows if the reverse would be the case .The test center where I’m going to take the test does not have seperate rooms for those who take the writing section and those who do not. They will ask students who take the writing to stay in and those who do not to leave the room after finishing the Science section. So I wonder if I leave the room after completing my Science section, whether I would receive an 1 or 0 for my writing score ? and what will happen to my score if I stay but do not write down anything ? In short, I want to find a way not to do the writing test but at the same time it wouldn’t affect my score. Any advice ?
Thanks in advance !!!

why not give ACT a call? In checking with college board for SAT, I found out my kid just need to tell the test center the day of the test…not sure whether it is the case for ACT