Yes, US is the only war monger in the UN.
You can put the UN on the planet Mars and it won't make a bit of difference. Its physical location has no bearing on its operations. The issues are structural, an organization that was created after World War II and changed very little since then. It doesn't reflect the geopolitical reality of the 21st-century.
I know people like to blame the US for hijacking the UN, but this is a laughable charge, at best. US is only one of five members with a permanent veto. What about the other four, including China and Russia? They will use their veto power to serve their interests, but somehow it's wrong for US to do the same.
Whether US leaves the UN, or gets kicked (both unlikely), a UN without US is a useless organization. Nothing will really change except the players.