This can differ depending on what browser you use:

Google Chrome:

• From the “Menu”   button in the upper-right corner of the Chrome window, choose “More Tools” > “Clear browsing data…“.
• Click "Advanced"
• Select the period of time you wish to delete cached information using the “Clear the following items from” drop down menu. From there, you can choose “Cached images and files“.
• Select the “Clear data” button, and Chrome will clear your cache.

FireFox:

• From the History menu, select Clear Recent History.
• If the menu bar is hidden, press Alt to make it visible.
• From the Time range to clear: drop-down menu, select the desired range; to clear your entire cache, select Everything.
• Next to "Details", click the down arrow to choose which elements of the history to clear; to clear your entire cache, select all items.
• Click Clear Now.
• Exit/quit all browser windows and re-open the browser.

Safari:

• Click Safari in the upper left hand side of your screen. In the menu that appears, click Preferences
• In the window that appears, click the Privacy tab. Click the button Remove All Website Data....
• Click Remove Now in the pop up window that appears.

Internet Explorer:

• Select Tools (via the Gear Icon) > Safety > Delete browsing history....
• Make sure to uncheck Preserve Favorites website data and check both Temporary Internet Files and Cookies then click Delete.
• You will get a confirmation at the bottom of the window once it has successfully cleared your cache and cookies.