Open the Settings app
Tap Safari
Tap Clear History and Website Data
Tap Clear History and Data to confirm
To remove cookies without clearing history, tap Advanced
Tap Website Data
Tap Remove All Website Data
Tap Remove Now to confirm
To delete cookies for a specific site, tap Advanced
Tap Website Data
Swipe left on the site name
Tap Delete
To block future cookies, go to Settings
Tap Safari
Turn on Block All Cookies