The officials said in a statement on Saturday that they had re-examined their decision after a "significant and relevant new element" emerged, which was unavailable to Williams at the time.
A second hearing carried out virtually on Friday then rescinded the original penalty handed to the Spaniard at Zandvoort on August 31 for causing a collision with Racing Bulls' Liam Lawson.
The stewards had blamed Sainz, who was trying to overtake around the outside at the first corner after a safety car restart, and handed him a 10-second penalty plus two penalty points on his licence.
Sainz had said at the time the penalty was "a complete joke".
The new stewards' statement said they now agreed "with Williams' characterisation of the collision as a racing incident".
"The Stewards are satisfied that the collision was caused by a momentary loss of control by Car 30 (Lawson). However, in the Stewards’ assessment, no driver was wholly or predominantly to blame for that collision," the statement said.
They said Sainz had contributed to the incident with a risky move that ultimately could have seen him run out of track, or collide, had the coming together not happened when it did.
Sainz served his time penalty during the race, and the classification cannot be changed, but stewards noted that the gap at the end between the Spaniard and the car in front of him was 17 seconds.
"The decision having been rescinded, it follows that the two penalty points imposed on the driver of Car 55 (Sainz) are to be removed," the stewards said.
Williams had presented three elements it said were new, significant and relevant - including footage from the 360-degree camera on Sainz's car and from the rear facing camera on Lawson's car, which could only be accessed after the race.
Sainz's own account of what happened could also only be heard subsequent to the penalty.
The footage from Lawson's rear camera showed the momentary loss of control by the New Zealander "resulted in Car 30 colliding with Car 55, not the other way around," the statement said.