You can enable or disable the ability of users to search the content of a Website Release.
If enabled, a search icon will appear at the top right of your web allowing users to enter a term to be searched on, powered by Google.
The Show Site Search checkbox is in the Template Presets tab.
To navigate to this tab, click the Hamburger icon at the top left of the Platform interface, and locate and click the Template Presents link.
The Show Site Search checkbox is at the bottom of this settings page.
After checking or unchecking the box, make sure to click the SAVE button at the top right of the interface.
Any Website Release using this template will have search enabled.
To learn more about Template Presets, see this document: Manage Template Presets