No, more advanced human civilizations could not have existed and us not know about it. The mark that a civilization on our scale makes is a very big impact on the world around us so much so that it would be fairly obvious that any culture any where near our level of technological or global reach would be severely obvious. Despite what nat-geo and the history channel say about our buildings falling apart and such. Even if all that were left were the natural world and all the rest had vanished our resource extraction and farming practice remnants would make it obvious.
There could be civilizations that we have not found that have raised up beyond the level of what we commonly expect for the age that it was around in though. The reason we wouldn't have found them is because we destroyed the artifacts accidentally, there are sanctions on looking in those regions of the world, or they are very dangerous to look into those regions.
Also we have a pretty solid understanding of how our species spread, when and where and we have a general outline of history from the point from which it were possible to start having civs on Earth by humans to present so it is almost impossible for an advanced civ to have been on Earth without our knowledge.
That being said, if you're a super advanced alien race you could probably cover your tracks, however any ancient alien myth completely throws this idea out because ancient aliens either came to help and thus it wouldn't make sense to cover themselves up or were tossed out which means they simply couldn't cover it all up.
Edit: I want to add that if a race wanted to cover up that they were here so that it would be really hard to figure out it would take a very long time to do, literally millenia if not millions of years and complete resurfacing of the planet to the degree that it's really not a reasonable thing for such civ to do as it implies they'd be extremely hostile.