This document explains how to clear Safari’s cache and cookies on iOS.
Note: these screenshots were taken on an iPhone running iOS 5.1, but the same general procedure can be used on other iOS devices such as the iPod touch and the iPad.
1. From the home screen, tap the Settings button.
2. On the Settings screen, scroll down and tap the Safari button.
3. Under the ‘Privacy’ section of the Safari screen, tap the button labeled Clear Cookies and Data.
4. On the confirmation screen, tap Clear Cookies and Data.
Article Source: helpdesk.wisc.edu