While there isn't really any way to completely empty the TC, if you are willing to remove the pan you there is one more thing you can do to remove a fair bit more fluid.
With the pan off, you will see the strainer attached to the valve body. You will also see a tube crossing over the strainer that would prevent removing the strainer. There are two black 10mm bolts holding the tube in place. Remove those two bolts and slowly wiggle the pipe loose being careful not to bend the pipe. When this pipe pops loose, a SIGNIFICANT amount of fluid will drain from the TC. I believe this will empty about half the fluid from the TC.
You can then change the strainer if you so desire, it isn't really necessary as this isn't a filter as much as a strainer screen. Torque on all bolts inside the transmission are 8Nm or 70inlb. Pan bolt torque is 4Nm or 36inlb.
Good luck