Hello I will help you with your question,
The spring clips are removed with a pick tool that you can bend out of a large paper clip. Just hook the clip and pull it out of the fitting and you can remove the line from the fitting by pulling straight back. Keep control of the clip as you remove and insert it as they like to fly off to never never land. You can get replacement clips at your local autoparts store but they are expensive ($4)
Here is the service information to remove the clips and lines
Transmission Oil Cooler Line Quick Connect Fitting Removal Procedure Important: Perform the following procedures when removing the retaining ring and cooler line from the quick connect fitting on the radiator and transmission.
Installation Procedure Important:
Let me know if you have further questions about this
I see none of the images posted, lets try this again
Sorry I just saw your feedback, There is no need to drain the system just put a catch pan under the area and clean up after you are done then top off the trans if needed. (not often needed)