URGENT! Can you withdraw from an SQA exam on the morning of the exam?

I really don't feel ready to sit my exam tomorrow afternoon. It is an extra subject (4th Advanced Higher), which I don't actually need, and I have all unconditional uni offers. It is purely 100% exam assessed, so I haven't had to complete any coursework/units.
If I contact my school first thing tomorrow morning, would I be able to withdraw and not sit the exam in the afternoon?
Otherwise, if I simply don't turn up, I know I will get a 'No Award'. Does this data get sent to unis?

Ye I agree, there's no point in sitting through a whole year of classes to give up right at the end. Go for it and you might even shock yourself and do way better than expected.

@DerDracologe any advice?

Id turn up and give it my best shot, probably won’t be as bad as you think. Also if the school entered you for the exam they might charge you for the entry if you dont turn up. You’ll get no award on your certificate, i think you have to submit the grade to unis on ucas ( @McGinger can you comment? ) because you were entered and it’s too late to withdraw so far as I know.

'Unconditional' still relies on your completing the qualifications you said you were taking.
If you dont take the exam, you may be risking having that offer withdrawn.

This qualification wasn't listed on my original UCAS, as I took up the course in February.

I don't know what the SQA withdrawal deadline is. If the school withdraws me from the exam, it shouldn't show up as 'No award' but if I don't turn up, it will.

What's the harm in taking it anyway, even if you just write your name?

A 'No Award' or a poor grade undermining my other results. Would mean if I wanted to switch uni course/reapply to another uni, this would show