One way to break this habit: when the dog jumps up, you say "DOWN!" firmly. At the same time, step lightly on a back paw, and give the collar a jerk downwards. As the dog is up, reaching to step on a rear paw should be easy. You want the dog to feel the pressure on the paw and the downward jerk, but you don't want to hurt the dog. Uncomfortable, yes; hurt no.

Another method: When the dog is up ignore the dog. Do NOT react or respond as this is not behaviour you want to reward. No eye contact, no talking to the dog. When the dog is down, tell him "GOOD boy, Spot!"

OR if you are holding the leash and the dog is jumping on someone else, the other person must ignore the dog while you give the leash a jerk to get him down.