When we start and configure the OnePlus smartphone for the first time, we are immediately greeted by the Google search bar on the home screen.
Google search can be removed like a normal widget by tapping and holding to adjust the home screen to your own wishes and usage needs.

Note: The Google search bar can be added back at any time through the widget settings.

Android 10 | OxygenOS 10.0
Step 1:  Tap and hold the  Google search bar
Step 2:  Tap on  Remove
  1. Tap and hold the Google search bar
  2. Tap on Remove

OnePlus Instructions