Google Chrome:

1. Click the Chrome menu on the browser toolbar.
2. Select Tools.
3. Select Clear browsing data.
4. In the dialog that appears, select the checkboxes for the types of information that you want to remove. (Make sure to select Empty the cache & Delete cookies and other site and plug-in data)
5. Use the menu at the top to select the amount of data that you want to delete. (Select beginning of time to delete everything.)
6. Click Clear browsing data.
7. Quit and restart Chrome.

Safari:

1. Click on Safari > Reset Safari...

2. Check both Empty the cache and Remove all cookies, then click on the Reset button.

   Note: In newer versions of Safari (v5.1.x), these two options have been replaced by a single checkbox, Remove all website data. Checking this will clear both the cache and cookies.

3. Quit and restart Safari.
   
   

Mozilla Firefox:

1. On the menu bar, click on the Firefox menu and select Preferences...
2. Select the Advanced panel.
3. Click on the Network tab.
4. In the Cached Web Content section, click Clear Now.
5. Quit and restart Firefox.
   
   

Internet Explorer:

1. Open Internet Explorer by clicking the Start button. In the search box, type Internet Explorer, and then, in the list of results, click Internet Explorer.
2. Click the Tools button, and then click Internet Options.
3. On the General tab, under Browsing history, click Delete.
4. Select the Cookies checkbox, and then click Delete if it isn't already checked. Clear or select checkboxes for any other options you also want to delete. If you want to keep cookies for your saved favorites, select the Preserve Favorites website data checkbox.
5. Quit and restart Internet Explorer.