Open Settings
Tap Safari
Tap Clear History and Website Data
Confirm by tapping Clear History and Data
To remove only cookies, tap Advanced
Tap Website Data
Tap Remove All Website Data
Confirm by tapping Remove Now
To delete cookies for a specific site, go to Settings
Tap Safari
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