As US President, does Joe Biden have the power to directly take on the NRA & ban all guns in the US? ?

No, of course the President cannot by fiat overrule the constitution.

It's not the NRA, it the constitution and the number of court rulings on the 2nd, he would be going against. The president does not have that sort of power.

Go ahead I'd like to see Joe try.

Note to Libtard: The US isn't the UK.

As a rising Dictator YES!

As a fellow citizen, NO! 

He needs to call a constitution convention to Repeal  the 2A.   In FACT the whole of the first 10 amendments need to be repealed for there to be Real Law & Order under the constitution.

It is Constitutionally impossible, otherwise, since that particular amendment is worded with "Shall not be Infringed".  Many States have already "Infringed" and have so for many years. Massachusetts first, Then Tammany Hall (NYC).

Disarming the Police would be a first Step.   If the coppers don't have guns, then the criminals won't need them either.  The criminals could be using socially acceptable weapons that are quiet, like knives, just as they do in the U.K. (well actually they use straight razors.) 

That would be impossible the way laws are in the US. There are more guns than people in the US and they defend their right to be able to shoot each other. 

Since Biden has not said he wants to ban all guns it unlikely to happen 

The bad guys would still be heavily armed. .......Now what? 

Define 'take on the NRA.'

He certainly has what is called the bully pulpit of the Presidency. But, banning guns are a matter of law, and Congress is the branch of government that makes actual laws.