How to disassemble this small Technic turntable, combination of parts 99009 and 99010?
These parts do not come apart. They are designed to be clicked into place and then remain connected. I have not found nor heard of a way that these can be separated without damaging the plastic and hence the functioning of the part.

The assembled component has part number 99009c01 - Technic Turntable Small, Complete Assembly with Black Outside Gear Section.