Before I submit a bug, I wanted to run it by here again. I’ve seen this topic with no working solutions. When you Emulate 3 Button Mouse when using Left Click Select, you can select edge loops by holding Shift and double clicking. You should be able to Deselect edge loops using the same combination but you cannot. There seems to be no way to Deselect edge loops without going into settings and turning off Emulate 3 Button Mouse temporarily (which is what I have been doing). I kept thinking they would fix this issue with a new release but alas, we are now 4 versions into blender 2.80 with no solution.
If anyone knows something that I do not, please let me in on it. Otherwise, I will submit an official bug because this really seems like a no-brainer. Shift Double Click should do both select and deselect when it comes to edge loops.