I thought I read that this was in this version.
If so how do you do this as I have not seen it yet and could have done with pulling my horse out who came down with a virus but I didn't spot it till the day.
Or have I mis read that it would be in the game.

Not misread Fairy, it was on the new feature list, I havent tried it myself yet - what type of game are you playing, and is it flat, jumps or combined?

Just playing about with all types of game at the moment.
Just have not seen the option on race day yet and just wondered if I am missing it or do you have to do it before you arrive at the course through another screen.

I think you just go to declarations and remove horse as you would normally. On SO4 you could only do this the day before the race, now you can do it the day of the race. Unless I'm mistaken and you can withdraw a horse even when you've gone to course but i don't think so

i did this as my 2yo got sick on day of race.
Go onto decs screen and remove the race as usual. so.......
dec screen, click red circle after horse name. Click date on right hand side and scroll down to your horses entry.
Click remove horses entry

Thanks.