Should NATO have been disbanded after WW2?

NATO didn't form until a couple years after WWII.  And it benefited America tremendously. 

Washingtons farewell address, which contained, among other things, a warning against entangling alliances, was written when the US was weak. In 1796, the US was a fledgling country with an almost nonexistent military and porous borders.  They claimed nearly half a continent but had effective control over only a small portion of it.  Foreign military bases still existed in territory the US claimed (and which was guaranteed to them by treaty).  There were no other independent American nations.  The US existed in an Atlantic system dominated by powerful European empires, with fortunes, populations, and militaries which dwarfed those of the United States.  And this came after Washington faced the question of how to respond to the French Revolution.  America had signed a mutual defense agreement with royalist France, but Washington abandoned it after the French Revolution progressed to war.  This was probably smart.  Drawing the US into a European war would have been disastrous.  Washington's warning thus made sense, in its time. 

But in 1949, four years after WWII, when NATO was founded, the opposite made sense.  The US was no longer a small weak nation.  It was the largest economic, industrial, and military power on earth.  It had the power to get involved overseas.  Moreover, the US had just come off a powerful demonstration of he perils of not getting involved.  Following WWI, when the US had lost tens of thousands of lives in a European war which didnt' seem to benefit it much, the country turned isolationist.  America didn't want to get involved in another European war, or any other major foreign war, and sat back while Germany and Japan gobbled up large parts of Eurasia.  But the war eventually came to them anyway.  Trying to be isolationist didn't work.  All it did was ensure that America would have to fight a much more powerful enemy when they did get involved.  After WWII everyone realized that it would have been better to stop Hitler at Munich, or before, rather than wait for him to get too big to deal with easily.  Better to nip problems in the bud before they could become big ones. 

That's the purpose of NATO.  The founding reason for it is to prevent war.  Rather than ignoring problems and hoping they'll just go away, it seeks to prevent them from ever happening.  As the old saying goes: the purpose of NATO is to keep the US in, the Soviets out, and the Germans down.  The point of NATO, at its inception, was to prevent another European war by making the prospect too costly.  Any Soviet adventurism in Europe would result in a confrontation with the US, which meant a nuclear confrontation, which meant annihilation.  It raised the stakes so high that no one was going to try anything.  By linking most of non communist Europe in a defensive pact it ensured that there could be no further serious violence.  And it worked exceptionally well.  In the 40 years before NATO was formed there were two general European wars, costing millions of lives and doing immense damage to countries across the continent.  In the more than 70 years since the founding of NATO Europe has been almost entirely at peace (the exception being the civil war in the former Yugoslavia).  Without NATO the US could very well have found itself either in a shooting war with the Soviet Union or in a world dominated by Soviet hegemony

Your facts are a little inaccurate.

George Washington was correct in his assessment. However, you're talking about the League of Nations, not NATO.

And while you believe the malarky you've learned about WW2, Japan was provoked into attacking the US by FDR because 1) His New Deal programs that were meant to pull the US out of the Great Depression were failures, and thus he needed a war to create employment and stimulate the economy, and 2) He was influenced by the Jewish advisers that he kept close at hand - Jews ("Zionists") who had already declared war on Germany in 1933.

Hitler didn't want war. As long as Roosevelt was unable to get Congressional approval to involve the United States in the European conflict (that Roosevelt helped provoke), the United States was no threat. As soon as Japan was provoked into attacking, Hitler knew it was a matter of time before the US came after him.

Once Japan attacked, it automatically involved Germany.

Considering it was not founded until four years after WW2 that would have been a bit of a strange thing to do. It had some relevance when the Soviets formed the Warsaw Pact in the 1950s.