Verbs:
* Butt out: This is a very informal and direct way to say someone should stop interfering.
* Mind your own business: This is a classic phrase that directly tells someone to stay out of others' affairs.
* Don't meddle: This suggests that the person is interfering in something that doesn't concern them.
* Refrain from interfering: This is a more formal way of saying someone should not get involved.
Phrases:
* Keep your nose out of it: This is a strong way to tell someone to stay out of someone else's business.
* Let them handle it: This implies that the person has the ability to deal with the situation themselves.
* It's none of your concern: This clearly states that the situation is not relevant to the person asking questions.
* Respect their privacy: This is a more polite and respectful way to say that someone should not pry.
The best choice will depend on the specific context and the relationship between the people involved.