Imagine you have lived in a nice neighborhood for years, there are some folks up the road - you are not best friends, but, you say hello and exchange plesantries.
One day, you discover that those people are actually your parents.
Would a good christian walk up, bang on the front door and say “I just discovered to my horror that you are my parents”?
That is how your first post comes across.
You were baptized Catholic. That means that your parents decided to bring you into the Catholic faith, just like they decided of which country you would be a citizen.
You can choose to reject that citizenship and you can choose to reject your Catholicism. There is a formal process for both, a good Christian would respect the laws and customs of his country of origin and of his Faith of origin, and do the research and follow those steps.
Or, maybe, he would also do some study and see that it really is a great thing to be a citizen of that country, and work to embrace it.