General Unwanted Advice:
* Backseat driver: This one is perfect for someone who constantly tells you how to do something, even when you're already doing it.
* Know-it-all: This describes someone who assumes they know everything and offers their opinion on everything, even when not asked.
* Unsolicited advice: This is a more general term for any advice given when it's not wanted.
* Butting in: This describes someone who interrupts and gives advice without being asked.
* Meddling: This implies someone who interferes in other people's affairs, often with the intention of giving advice or "fixing" things.
Specifically about directions:
* Telling you how to suck eggs: This is a British idiom that means giving someone obvious or unnecessary advice.
* Telling you how to do your job: This implies that someone is giving advice that is seen as intrusive and disrespectful.
Other options:
* Giving unsolicited opinions: This emphasizes the person's tendency to share their thoughts even when they are not wanted.
* Always got to have their two cents in: This refers to someone who always feels the need to share their opinion.
The best idiom to use will depend on the specific context and the tone you want to convey.