Click the Tools menu (three dotted lines in the upper-right corner).

Select History.

Select Clear Browsing Data from the left-hand side. Set the Time Range set to All Time. Check-mark Cookies and other site data and Cached images and files and select Clear Data.
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If on a Windows computer, close and re-open Chrome to save your changes. If on an Apple computer, go to the Chrome menu on the top menu bar and select Quit for the changes to take effect.