Whenever people justify why the US's jury system is better than the judgement by judges that's prevalent in continental Europe it's always about these exact scenarios. If you just want to find facts you don't need a jury of peers. The jury is at least in part there to pass a moral judgement beyond the letter of the law.

From what I understand a juror can only be removed during the jury selection process or if someone outside the jury "tampers" with the jurors. If you get called to jury duty, the quickest way to get out of it is to say you know about jury nullification. But if you don't reveal that and get into the jury you are free to rule as you want and to try to convince the other jurors to do the same.