1. Click the three vertical dots icon in the top-right corner of the screen,
2. hover over "More Tools",
3. and then selecting "Clear Browsing Data."

Then select "Cached images and files".

If you decide to clear "Cookies and other site data" make sure you download (and store safely on another device) your key pairs and public keys before clicking "Clear data".

More detailed information can be found at How to Clear Cache and Cookies in Google Chrome