There are two ways of saying it. ¿No quieres parar de hablar? Which would imply that the person is speaking too much but not in a conversation, but a monologue. Por favor, que pare de hablar. Please, make him stop talking. The second form is using the verb "dejar". ¿No quieres dejar de hablar? Which would imply that the person is participating in a conversation and it would invite to continuing the conversation, maybe even after having said goodbye. Tengo que irme, pero no quiero dejar de hablar contigo. I have to go, but I do not want to stop talking to you. I hope this helps.

Don't you want to stop talking? Literally: ¿No quieres parar de hablar? But we don't say the sentence that way. If we want someone to stop talking, we say the sentence in affirmative: ¿Quieres parar de hablar? If you're a bit angry you'll probably say: ¿Te quieres callar? or ¿Porqué no te callas? In any case we don't expect an answer to these questions because they're rhetorical and only a more polite way to say "Stop talking" or "Shut up", like in Englis I think.

¿No quieres parar de hablar?