No you can't disbud him like you would a younger kid. Your options now are to just keep the horns cut back as they grow, or go to the vet and have them cut them out. I've only ever had the 2nd option done once... I didn't know the full extent of what the vet had planned on. It went ok and the kid had a nice smooth head, but I wouldn't do it again. You could just tell she was not feeling very good for a couple days. It opens the sinus cavity, they literally scoop the entire horn and base. You have to keep it packed for awhile and covered. Trying to keep a guaze covering on the kid's head for any length of time is almost impossible.
A couple less than ideal options are banding and paste.
Please DO NOT USE the caustic paste. You can't keep it in the right spot, it can get in the eyes and cause blindness, it rubs on off on other areas and causes burns.
Banding... it's hard to keep the bands in place. You're not guaranteed a clean break, when they get thin, they just bust off and cause bleeding, etc.