It's the round red, yellow, blue, and green icon typically found on the home screen (iOS). If you're using an Android, you'll find it in the app drawer. You can stop typing once you see the suggestion you don't want to see. A pop-up will appear, asking if you want to remove the suggestion from the history. Now that you've removed this URL from your history, it will not be suggested when you type into the address bar.

Summary:
Open Chrome. Type a URL or search keyword into the text bar. Tap and hold the suggested search term or URL. Tap OK.