The one on the right I just unscrewed the bottom half, and on the left I removed the whole thing. Both ways are real easy.
I used a drill press. To be sure I marked each side, and drilled a pilot hole on center first, on both sides, then used a 0.500 inch drill to make the final hole. I did not remember if I checked the pin in my drill index to see if it would go in a hole smaller than 0.500 inches, but I think the original hole is very close to 0.5 inches.
I think it would be much better to drill them in a drill press if you have one. More likely to get the holes square that way. Then again, considering what they do, drilling by hand would probably be good enough, if you are fair at drilling. I would not try to drill them in place myself. Too easy to take them of and put them in a vise and press downwards...
Attached is a photo that someone else posted. Sorry I don't remember who. I did essentially the same thing. As the lower links go down, the tractor side of the clevis get closer to the lower link arm. If you put the new hole too high they might hit. In my case 1.25 inches left about 1/8 inch clearance, maybe a shade less...