Do monkeys have disposable thumbs

No. No animal or human has disposable body parts.

Perhaps the intended question was "Do monkeys have opposable thumbs?" The answer to that question would be -- yes.

Almost all primates have opposable thumbs used for grasping things, especially tree branches, and picking up things. Humans, apes, and most monkeys have this type of thumb. Humans have more flexibility for manipulating small objects and they can move their thumbs across their hands much better and farther than any other primate giving humans the most dexterity of all primates.