What does "shut someone down" here mean?

Native speaker’s answer
Rebecca
To "shut someone down" is an informal expression meaning to reject, strongly discourage, stop, or prevent something from happening. Thus, the speaker says "I'll shut you down" to share the warning against regulation-breaking that he received. Ex: I wanted to go on holiday to Hawaii, but my parents didn't like my idea and shut it down immediately. Ex: I tried to get that girl's number but she shut me down.