If you’re security conscious, you may want to occasionally delete the record of your Google Now activities, whether that’s wiping your entire Google Now history or just removing the record for a certain day.
Head over to history.google.com/history. Open the side menu and make sure Web & App Activity is selected. Now tap the three-dots menu icon and then select Delete Options. Select either Yesterday, Today or Advanced from the menu.
If you select Advanced, you can then choose from Past 4 weeks or All time. Select Delete, read the warning and confirm the deletion. Open Google Now and tap the search bar to see whether your history has been completely cleared.
Sometimes queries may remain in Google Now even after you have cleared your search history. If past queries do appear when you tap the search bar, you can delete them manually by long pressing and then selecting Delete.