Leave the strongest and pull the others up. You can use the leaves in salad.

Make sure they are beetroot before you pull them out, personally, i'd thin to 2 seedlings then to one in a week or two depending on the strongest.

Thanks again, I sometimes think I'm asking the silliest questions but you guys seem to happily put up with them, for which I'm very grateful.

There is no such thing as a silly question just a silly answer!

the only silly question hank is the one you DON'T ask !!!!

Just a thought, beetroot seed are so large do you need to sow more than one at any point?

I never sow more than one at any point, but every year they come up in ones, twos and 3s. And I've always been told to soak them for a while before setting them which I do.

Beetroot seeds are clusters and will produce 2/3 beetroot plants but you can also buy monogerm seeds such as solist/monata that only produce 1 plant which saves having to seperate them interesting link about beetroot seeds below
http://www.vilmorin.ru/upload/brochures/Beetroot%20info.pdf

Thanks Steveg, I just looked at the website you mentioned. S'a bit technical for me but I wanted to ask them why they make beetroot seeds with 3 seeds inside, when one has to pull up the weaker 2. But there didn't appear anywhere to ask a question.

hi hank they don,t make beetroot seeds with 3 seeds inside, i read that beetroot seeds can have up to 6 seeds inside , i guess there like a conifer cone which if planted then opens and has lots of seeds inside so thats why u plant them sparely .

Oh boy, I knew I was doing wrong looking at the technical website ( Vilmorin etc ). I guess I scanned it, saw something I thought I recognised but I didn't really, then jumped to a wrong conclusion.
So thanks very much guys, but as a beginner (still), I'll just set 'em and watch 'em grow. ( I hope )