James K has already covered the historical part as to what was once temporary was later came to be interpreted as permanent, so I'm going to cover the part about removal of the Art 370.
I suggest you read the Article 370 at least once for a better understanding.
Unlike other articles of the Constitution of India (CoI) which can be amended or repealed via Article 368, Art 370 can be made inoperative per Clause 3, as in to be a dead letter, but not officially repealed.
For the article to become inoperative, the President of India, under Article 370(3), has to issue an Executive order after receiving the recommendation of the Constituent Assembly (CA) of the J&K. However, the CA ceased to exist a long time ago, thereby introducing a great difficulty for the President at any point in time, if felt needed be, to make the article inoperative.
This problem was solved, as witnessed in the Executive order, by President R K Singh, aided by his Prime Minister N Modi and his Council of Ministers, rather cleverly and perhaps unconstitutionally, by using the same process and privileges that actually granted the state of J&K special privileges.
What transpired is this:
For all intents and purposes, the Union Government interpreted the meaning of "Government of the State" (of J&K) in Article 370 as the incumbent Governor of the State. They overlooked the fact that the said article with the note "Explanation" explained that as the person being aided and advised by his Council of Minister, though the Governor was not aided and advised by any such Council when his concurrence was sought by the Union Government to remove the aforesaid difficulty for the President.
Marching on with this interpretation, the President under Art 370(1)(d) amended Art 367 (with respect to J&K) under his order and changed the meaning of CA of J&K to Legislative Assembly (LA) of J&K. This was the biggest difficulty for the President to make the Art 370 inoperative at any time.
Through that same order, all special privileges to J&K have been dismantled using powers from the same Article 370(1)(d), all provision of the Constitution have been imposed on the State, and its very statehood stands endangered by the J&K Reorganisation Bill, 2019 which would bifurcate the state into two UTs.
With the order of President whole Constitution is applicable on the J&k, and given that the state is under President's rule, the Parliament has all the powers under Art 356 to perform all and any function of the LA of the state. It is this power that the Executive is putting the Parliament to use by having the resolution for making Art 370 via its clause 3 fully non-operational, except where it says that Art 1 is valid, thereby ensuring only one thing in Art 370 that the state is an integral part of the Constitution.
I strictly suggest reading this piece from The Hindu as it explains clearly what has happened with Art 370 after the recent changes on Aug 5, 2019.