iOS, Android, web? What are you on? What type of channel? Try this:
Sign in to YouTube Studio: Access the YouTube Studio platform.
Navigate to Customization: In the left menu, find and select “Customization”.
Locate the Home tab: Within the customization options, you’ll find the “Home tab” section.
Toggle the Home tab off: Turn the toggle switch next to “Home tab” to the off position. This will remove the search bar from the menu bar.
Try toggling the switch.