In order to delete the search history on YouTube
in your iPhone, open YouTube app. Now tap on this icon at the top. Select “Sign in”. Now select the account whose YouTube search
history you want to delete. Then after that tap on “Library”. Now select “History”. These are the videos which I have searched
in YouTube using my account. So, if I want to clear this search history,
select on this menu option at the top. Select “History settings”. Now scroll down. Select “Clear watch history” and then select
“Clear watch history” to remove the YouTube search history from your iPhone.