Until what age should the government force kids to be at school?
It's 18 in a lot of states.
In California you can leave at 16 if you have parental consent and pass an exam to show you are competent.
Other places if you have full time employment or training elsewhere, such as wanting to do an apprenticeship, sometimes as young as 15.
I think forcing someone to go to school against their will is never good. If you're able to work at 15 and want a job, go for it.
The government shouldn't force you to be somewhere you don't want to be.