I believe the "removable watermark" is meant to denote that it is not part of the picture when you buy it. Not that it is removable from the image as is.
It can be done, but you would need to find the same watermark on a black backgrounded image. then make a mask with it in photoshop and use it to "cancel out" the one on your image.
There is a special tool which helps to remove visible watermarks photo stamp remover
But I am not sure that it help you, your watermarks seams to be too complex.