water down
US /ˈwɑː.t̬ɚ daʊn/
UK /ˈwɑː.t̬ɚ daʊn/

1.
to make something weaker or less effective, especially by adding water or by reducing the strength of an argument or proposal
:
•
The company decided to water down the new policy after employee complaints.
•
He tried to water down his controversial statements during the interview.