An "E" clip is shaped like the letter E if you look at it the right way. Take a small flat blade screwdriver, NOT a Phillips, and place the tip between the "center" of the E and one edge. Keep the tip at a 90 degree angle to the linkage pin and gently twist the blade towards the center of the "E". The clip will rotate and come right off. It will go flying, so keep your hand in front of it. Again, eye protection is recommended.
This will work, but is not as easy and has more risk of damaging the clip.
To reinstall the clip, place it flat on the linkage pin with both ends in the "groove" on the linkage pin. Sounds complicated, but you'll see what I'm saying when you do it. Use needle nose pliers (regular pliers may do in a pinch) to "squeeze" the clip back onto/into the groove. The teeth of the pliers need to be placed at the center of the "E" and directly opposite (slightly over the edge of the linkage pin) which is easier done with needle nose. If your pliers slip, the E-clip may go flying, so be prepared for that. A bunched up rag or towel beside it should catch it if it does. Again, eye protection is recommended. I have reinstalled E-clips with a flat blade screwdriver on occasion, but really recommend against it.
chris