Youtube URL autocorrecting to "youtube.com___" in search bar

If you don't wish to delete your entire browser history, you can pick the annoying item in the omnibox and remove it with shift+delete on Windows, or fn+shift+delete on MacOS.

It could possibly be a in your history, so auto-completing Clear your history by:

1) Click the 3-horizontal-lines icon Google Chrome Settings icon in the top-right corner of the window and select Settings.

2) In the Settings window, click the Show advanced settings link.

3) In the Privacy section, click the Clear browsing data button.

4) In the Clear browsing data window, choose the duration of time to clear browsing data for (the past hour, the past week, etc.) and select the items you want to delete.

5) Click the Clear browsing data button to delete the selected browsing data.