For Google Chrome browsers:
On your computer, open Chrome.
At the top right, click More.
Click More tools
Clear browsing data.
At the top, choose a time range. To delete everything, select All time.
Next to "Cached images and files," check the box. (Note: if "Cookies and other site data" are checked you may be logged out of saved websites, which is not needed)
Click Clear data.
More info here: https://support.google.com/accounts/answer/32050
For Mozilla Firefox browsers:
Click the menu button
and select Settings.
Select the Privacy & Security panel.
In the Cookies and Site Data section, click Clear Data….
4. Remove the check mark in front of Cookies and Site Data.
For more information about managing site data, see Manage local site storage settings.
5. With Cached Web Content check marked, click the Clear button.
6. Close the about:preferences page. Any changes you've made will automatically be saved.
More info here: https://support.mozilla.org/en-US/kb/how-clear-firefox-cache