The one from the expansion tank - man up!! Release the clip, and slide it up the pipe well out the way. Now wiggle/twist the pipe until it slide off. If its really stuck with accumulated crud then getting something blunt under the pipe can help, but you do run the risk of punching a hole in it if you're not careful. Alternatively take it off the expansion bottle end and remove it from the pump when its out the van.
The stubby one is a cruel joke, invented by a sadistic German gentlemen... You will need to release the spring clip and put it as close to the other one as possible (but there is not much room). Then, as you remove the pump the pipe should pull off, but is a pain as often you also need to release the spring clip again as it may still be clamping the pipe to the metal stub inside. Just wait, its almost even more fun getting it back on again!!
You might want to consider ordering one with your water pump, this way you can:
a) cut the old one off
b) not have to worry that one day you may need to change it!
Cheers,
Alex