We know that Gallifrey and the Time Lords haven't been completely erased from the universe though, otherwise the Racnoss in The Runaway Bride wouldn't have known who they were. And I think it's been said somewhere that Jack Harkness, prior to meeting the Doctor, had had dealings of some sort with Time Lords; he thought the War was just a legend though.
If Gallifrey was indeed destroyed across all time zones, as some here appear to be inferring, then such an event would wreak cataclysmic damage to all of history. The Time Lords most likely wouldn't even exist as myths and legends for the wider cosmos; they would never have existed. But as I've pointed out, other people do retain memories of them, which buggers this whole scenario up.
I don't see how that buggers up the idea that the Time Lords were erased from history, given that Series Five established quite definitively that a person could be erased from history yet still leave evidence of their existence (the photo of Rory) or memories of their existence in others who have time traveled (Amy remembering the soldiers).
And what about all those other people who weren't time travellers? And even though some effects of their existence might persist, people would still have no way of knowing exactly who they were (or rather, who they had been). I've probably not explained that very well, but I hope you get the idea.