At what point should I nix the potty chair?

My son is nearly three and has been using the potty quite well for about 6 months now. The only issue is, he only wants the potty chair. We have a toilet seat adapter, but he hates using it, and needs help getting up and down. A stool doesn't help, since he fell off the stool and busted his chin once he... show more My son is nearly three and has been using the potty quite well for about 6 months now. The only issue is, he only wants the potty chair. We have a toilet seat adapter, but he hates using it, and needs help getting up and down. A stool doesn't help, since he fell off the stool and busted his chin once he won't use it. So if we do the seat adapter, someone (me, usually) has to hold him there. So we still use the potty chair. It's a pain to empty and clean, but he rarely has accidents at home. But the daycare says he is refusing to use the big toilet, and I am now having to send him to daycare in pullups, or else he will be 'expelled'. I used to reserve pull ups only for long car trips and night time. Should I just take the potty chair away, or let him use it til he is tall enough to use a big toilet on his own?
Update: I;m not saying I would make him balance- I would probably just have to drop whatever I was doing 20 times a day until he's five.
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