To clear Safari browser cache on iPad iOS 7, iOS 6:

• Click on the Settings icon from the home screen of your iPad. 
• Select Safari option (left side of the settings screen). 
• Scroll through the list of Safari settings
• Select Clear History and Website Data
• To continue with the deletion process, tap Clear. 
• To return to Safari's settings without removing any data, select the Cancel button.

NOTE: When you clear the history on the iPad, the history is also cleared on any other devices you have signed in to your iCloud account.

Additional resources from a google search:

• How to Manage History and Browsing Data in Safari for iPad
  
• How to Clear Cookies, History, and Cache on the iPad
• How to clear your iPad cache, cookies and history
  
• You Tube Video
• How To Clear The iPhone/iPad Cache
  

for Android Devices

• Clearing the browser history on an Android Tablet
  
• How to clear data and cache to free space on your Android Tablet or Phone (you tube video)
• How to clear app cache and app data in Android 6.0 Marshmallow
• Clear All Cached App Data At Once on Android
• How to fix low space storage in your Android smartphone with easy steps (you tube video)