I would like to know if its possible to install bamboo floors (lock) method on existing stairs and floors that are tiled.Do I have to remove the tiles as the area is flat? The kitchen is tilled and the dining/lounge has carpets. I would prefer having the same throughout. Thank you.

The right way to do it would be to remove the tile first

If that's a "float" floor you are installing, no need to remove the tile from the floor, assuming the surface is flat.
The stairs on the other hand, may require that you glue the floor panels in place. If so, make sure the glue you use will stick to the tile.