When I first had my I pad air 2 and used google for searching the web... under the list of searches it used to have view history and what looked like a little clock type thing...and I would click on view history and then just click delete but now it doesn't come up with view history in the list as far as I know I haven't changed anything it just did it on its own.
I've never actually used the feature you are referencing before. But, I tried to find my Google search history just now and found it by tapping My Account, and then tapping My Activity,and then scrolling down to my Google searches. Then, under each search card, tapping the three dots on the right side, then tapping Delete. Hope this helps!