I can't say for sure, but I have an KDL 46XBR5 and it may be similar to the 52". The stand is most likely being held in place beneath the back cover like the unit I have.
After you unplug the tv, lay it on a flat surface with a very soft clean blanket so you don't scratch it up. Place the television face down with the stand facing you.
Now if you look very closely, you may see little arrows (they look like this : -->) and little triangles all over the place. Disregard the triangles altogether, but remove all of the screws that have little arrows (again, they are the ones with he "->" pointing to the screw. There could be anywhere from 16 to 24 screws.
Make sure you put them back exactly where they came, there are usually different sizes). A piece of cardboard with a rough diagram drawn with marker helps, just push the screws into the cardboard where they line up on the tv.
Once you remove the back cover, you will see the stand has two large brackets screwed into the back of the television. They are vertical from the bottom.
I have attached diagrams showing the removal of the back panel as well as the bracket for my KDL46XBR5. YOURS MIGHT LOOK DIFFERENT but should be somewhat similar or at least give you an idea to go by
Note: If I am not mistaken, there are two black insulated copper ground wires connected to the bracket. If you disconnect the brackets, you will need to figure out where to reconnect these ground wires most likely or remove them altogether.
Hope this helps