образумить

см.
[make sb see reason]
If you make someone see reason, you persuade them to stop acting foolishly and behave more sensibly.

Example: Mary wanted to drop out of medical school in her fourth year. Her father managed to make her see reason.

to throw cold water on sb — охладить пыл; образумить

Example: We were about to pay but our dad threw cold water on our plan saying it was a foolish thing to do. — Мы чуть было не отдали им деньги, но отец образумил нас, сказав, что это дурацкая затея.

cool sb down

to prick / burst the bubble — to make sb see the bitter truth of sth

see also
[охладить пыл]
[горькая правда]
[открыть глаза]