N-S, you say that he can be and is president regardless of his ineligibility, so it begs the question, why would he be removed if his election was valid, as you insist? If he is the president, despite the Constitution, then why wouldn't he just stay President? How is he to be constitutionally removed from office if his election was valid, as you claim?
Because when the election was held and the electoral votes cast and when he was sworn in there was no evidence that he was ineligible. All actions were legal when taken. Should a miracle occur and you actually produce evidence showing that he's ineligible you don't go back to square one. You take the step going forward of removing him from office. According to the Constitution, Biden then becomes President.