If you’re making a form for a specific group of people, e.g. just your internal staff, you might be interested in hiding it from external search engines. This will reduce the chances of members of the public stumbling across it, so your form will only be seen by the right people.
To do this, open a form from Forms and go to Settings > General settings. Turn on the switch next to Hide from external search engines, and save your form.
Once you’ve done that your form won’t show up in Google or any other external search engine.
If you want to be really picky about who has control of one of your forms, set permissions so that certain users are denied access. If you’re an admin, you can also change user privileges for everything on OpenForms.