No you can’t decide if he sits it but the school may decide your child cannot access the test. This will be the case if they are working below the Year 2 tables level I.e unable to do any 10 times table or 2 times tables.
Can I opt my child out of this test. He is year 3 right now, so will be sitting this test next year. He is dyslexic and has sequencing difficulties. He can't yet name the months of the year in order so understandably finds memorising tables difficult. Can I simply tell the school I don't want him sitting them?