I've recently gone through Sword Art Online and I must say it is by far one of the greatest anime I've seen. But there's one thing that bugs me.
After SAO was cleared by Kirito and Asuna was found in ALO, why didn't they just take her NerveGear off? After all, it's ok to die in ALO and the NerveGear shouldn't fry the brain of the user after they die in-game anymore. So Asuna should've been completely fine right?
The problem was that they didn't know what was wrong with Asuna at first and certainly didn't know that she was on ALO, if they did then they probably would have found about Sugou's experiments. even when Yui confirmed she could detect "mommy" up in the tree there was little time before Asuna's and Sugou's wedding. so at that stage Kirito's proof was
a blurry picture which has someone who looks like Asuna, easily explained away by ALO's developer as being a Titania NPC who is apart of the Grand Quest (remember that Oberon's supposed to be waiting at the top and Titania is his wife in Shakespeare's play A Midsummer Night's Dream so it would make sense that Titania would be waiting aswell)
a Navigation Pixie saying that her "mommy" is up in the tree, again could be explained off as a game object's bugged reaction to possible future content given that Kirito's Character is already bugged having it's SAO stats.
given that in the past when the NervGear was removed the player was killed I would think Asuna's parents would err on the side of caution. even if Kirito explained who and what Yui is it, it might be too unreal for them to accept the risk of Asuna's brain getting fried, at least not before the wedding, which I would think Sugou would get called in to give his thoughts, where we know Asuna waking up works against him (remember that she hates him and if she was to wake would call off the wedding).
Now, aside from what I said above, how Sugou could explain away Kirito's evidence that Asuna was trapped in ALO, he also has inside knowledge of the NervGear having not only access to the technology as being the head of Rect Progress but he also worked under Kayaba. He could easily add more worry to Asuna's parents that there could be possible brain damage because of how the NervGear works.
And up until this point there was no indication that the NervGear still wouldn't fry her brain if removed. Clearing SAO only allowed (if not by force) players to log out. While yes, Kirito did die in ALO, this can be argued that Kirito didn't technically die, as his Remain Light was still there and was resurrected by Leafa. One can compare this as being the same as one using the Divine Stone of Returning Soul (resurrect item Kirito got hoping to revive Sachi) while in the Death Game, just with a much longer timer (in ALO it was 10 minutes).
The reason they didn't remove Asuna's NervGear is because it would still fry her brain. In the beginning of the anime, Kayaba explained that the NervGear will create an electrical shock if it is removed while in use. When SAO was beat, the players were able to log out of the system. If instead of logging out, the players had their NervGear removed while in use, they would die. Asuna was one of the few that couldn't log out because she was trapped in ALO. If you watch the ALO arc, there is a scene where Asuna tries to log out using the administration console. If she was successful, she would have been able to remove the NervGear without a problem.
That being said, there was still the case where dying in SAO caused the player to actually die in the game. This was caused by the game itself having that in its program. Proof of this is in Kirito's death within ALO. He still had the NervGear on, but he didn't actually die. In this case, he could die all he wanted in-game as long as no one removed his NervGear.
To sum it up, removing the NervGear while still in use would kill the user. The issue with dying in-game was just a SAO specific program. With the creation of ALO, the dying-in-real-life program was removed. Along with ALO came the AmuSphere, a safer alternative to the NervGear. The AmuSphere was designed to eliminate the die-when-removed risk. That's why you don't die if you have the AmuSphere removed during gameplay. So, basically, AmuSphere and ALO are safe, but the NervGear and SAO are programed to kill you.
