With version 8 of the Mac's Safari browser, Apple simplified some maintenance options, including removing the comprehensive Reset feature found in prior versions. You can, however, still do many of the same tasks it performed, such as clearing the browser of old Web pages, cookies and other data.
Reset Browser History and Cookies
This option clears many items from Safari's browser history including the pages you've visited, the list of downloaded items but not the files themselves, searches, cookies and website data.
Launch Safari, click the History menu, and then click the selection, Clear History and Website Data... to bring up the Clear History dialog box.
Click the drop-down list of options to select the last hour, today, today and yesterday, or all history. Click the Clear History button to remove the data for the time range you selected.
Remove Cookies Only
Click the Safari menu, and then click Preferences...
Click the Privacy icon to show privacy management options. Click the Details... button to show a list of cookies and other data.
Select website names in the list, and then click the Remove button to remove the ones you selected, or click the Remove All button to remove all cookies. Click the Done button when you're finished.