Can a King/Queen be removed by the government?

What if, indeed? That’s what parliamentary and public debate is all about - thrashing out all the implications of each new proposal.

Fair enough. These are indeed two different questions, either or both of which may be of interest to the OP.

It would take at least three years in Sweden, if we should stick to constitutional law (it would have to be approved by two succinct governments, with a general election in between) but yes, it could happen (though I find chances today pretty much like zero). It could and did happen much more readily in the old days

Neither does the UK; when Edward VIII abdicated back in 1936 his “Instrument of Abdication” was just him declaring his wish to abdicate in writing. Then Parliament* passed a law declaring that he was no longer king and that his descendants wouldn’t have any inheritances rights to the crown (nor would he or them require royal permission to marry). Only once Royal Assent was granted in his name to the act did Edward VIII cease to be king. Just like in Japan it was a special law that applied only in that specific case.
*Canada, South Africa, and the Irish Free State passed their own laws with the same effect to demonstrate their recent independence under the Statute of Westminster.

I have to agree with Leaffan, at least as far as Canada goes. Constitutionally and legally, Elizabeth is styled Queen of Canada, though in everyday conversation between ordinary people, she is simply referred to as the Queen.

There are a few people in Canada who will refer to her as Queen of England, but they tend to be those who cannot wrap their heads around the fact that the two offices (Queen of Canada and Queen of the UK) are embodied in the same person.

So, simply “the Queen” works well.

It’s like our postage stamps. They don’t mention that they’re from the UK, either. Other countries’ stamps do, and their heads of state usually need to be identified by their country too.

as far as changes go it only took 1000 years or so to change that a woman can be queen rather than her younger brother . The changes come at the speed of glaciers.

The current king of Saudi Arabia, Salman, succeeded his brother Abdullah at age 79.

So effectively if Parliament wants the Monarch removed via legal means and the Monarch refuses to cooperate and withholds Royal Assent, then the House of Commons will lead a coup and install whomever they want?

Broadly so, yes. It would depend on the precise issue at hand. If the Commons was acting against the wishes of the majority of the public, that would be a potential break on the Commons. But if the monarch were in trouble for breaching the many conventions surrounding the operation of the monarchy and running the reputation of the Crown and/or country through the mud, then there’s little kidding which institution would win a battle of wills.

I thought that an important part of Parliamentary Supremacy was Royal Assent? Wouldn’t Parliament be acting unconstitutionally if it removed the monarchy without such assent? Could the UK Courts rule the Act to be invalid as not a proper power of Parliament?

That seems to be a structural necessity much like a majority vote.

Compared to Japan, it’s at a breathtaking pace.

You’re absolutely correct. But such a circumstance would have put us beyond a pale the country hasn’t been beyond in some centuries. If the monarch violated constitutional norms, then constitutional norms regarding parliamentary deference to the Crown may come under threat.

After all, technically Parliament violated the constitution in 1642, 1649, and 1689 when it went against the monarchy, but here we are.

Not if Parliament decides to change the rules and the public at large shows no sign of punishing them electorally for doing so (best assessed by first having a general election and/or referendum on the issue).

Parliament of the day assessed the situation as the monarch going against the constitutional norms.

In 1642, it was Charles who had sought not only to rule without Parliament, but also to arrest some of its members for their opinions, and eventually to raise an army against Parliament. In 1649, he had sought to re-launch the civil war against Parliament that he had lost. In 1688, James had fled, eventually to raise an Army with French support, but initially was deemed to have abdicated and to have been succeeded by his daughter and nephew (who just happened to be the only successful general against Louis XIV).

“Treason never prospers -
What’s the reason?
If it prosper,
None dare call it treason”.

There’s also the precedent of the regency for George III, where both houses essentially directed that the Lord Chancellor fake the king’s assent.

Again, this just demonstrates my point. If the Crown undermines constitutional norms, then it risks Parliament doing it too.

Excellent point.

For more: Succession to the Crown Act 2013 - Wikipedia

Something like that: https://www.nytimes.com/1990/04/05/world/belgian-king-unable-to-sign-abortion-law-takes-day-off.html

So here’s my question:
Suppose the House of Commons passes a bill to give 4.2 Billion pounds to Ms Polly’s Home for Precocious Pussies ran by (coincidentally) the PMs sister. Assuming the monarch refuses Royal Assent and the public does not support such a disbursement. The PM tries to remove the Monarch - are we sure Parliament would win such a battle?