You can delete cookies in Safari by going to the preferences and clicking the "Remove all Website Data..." option in the Security section of the preferences. You can click the "Details" button to do this for specific sites instead of all of them.
You can also choose the Reset Safari option in the Safari menu to check options to remove the cookies, and also reset other aspects of Safari.
To clear the cache only, go to the Safari preferences and click the "Show Develop menu in menu bar" option in the "Advanced" section, followed by choosing "Empty Cache" from this new menu.
You can remove cookies in Safari by opening Preferences (under Safari in the menu bar), clicking the "Privacy" entry on top, and then "Remove all website data".
Another thing you can do is also under Safari in the menu bar, you can click "Reset Safari". Among other things, that will clear your history.