Can you tile over existing cork flooring in bathroom?

It is not a good idea to install tile on top of anything that will degrade over time, is softer and more flexible than the tile, or is not securely set to the floor or sub-floor, as most cork floors are "floating" floors. Save yourself any aggravation and remove the cork. Chances are it will come up much easier than you might think, even if it's glued down.