dissuader
/ˌdɪsˈjuːdeɪdər/Definitions
1. noun
A person who tries to persuade others to abandon or give up an intention or plan.
“The politician’s advisors were skilled dissuaders who helped him reconsider his stance on the issue.”
2. verb
To persuade someone to abandon or give up an intention or plan.
“The coach tried to dissuade his star player from quitting the team during the season.”