withdrawing money is possible if you are verified at PokerStars then you will be able to withdraw money from PokerStars it is very easy and they do not delay withdrawing money, they do it in a couple of seconds and the money will immediately come to your account
OP is talking about a feature in PokerStars cash games, which allow players to cash out their
equity, when they are all-in before the river. This is also sometimes called "all-in insurance" and basically mean, that someone else (in this case the house) takes over the risk / variance. In the classic TV-poker show "Big Game" Phil Helmuth occationally purchased all-in insurance from some of the other players. Most online
poker sites have this feature in their cash games now, and usually the fee is 1%.
Example: You have QQ, the opponent have AKo, and you are all-in before the flop. Your chance of winning is 55%, and the pot size after rake is 20$. This mean, your equity share is 11$. If you use the all-in cash-out option AKA "insurance" you will be rewarded 11,00-0,11=10,89$ from the pot. If your opponent also opt to cash out, they will be rewarded 9,00-0,09=8,91$, and PokerStars thus earn an extra 0,20$ in rake. Alternatively if your opponent dont cash out, the board will be run out, and he will then either be rewarded the full 20$ pot or nothing with him now essentially
gambling with the house like in casino games.