You will need to rotate the cartridge holder to remove the remaining cartridges.

Insert a thin rod into the "barrel" shaped hold on the right side of the printer. This will disengage the cartridge holder lock. You will need to press and hold to keep the lock disengaged.

Press down on the empty cartridge slot. The carousel will begin to rotate.

Rotate the carousel until the cartridge pivot tabs line up the the alignment opening.

Repeat steps 2 and 3 until all toner cartridges are removed.