In Apple's Safari browser, clearing the cache is done via the Develop menu. Just tap or click Develop and then Empty Caches.
With a keyboard, clearing the cache in Safari is super easy with the Option-Command-E shortcut.
TIP: If you don't see Develop on your Safari menu bar, enable it via Safari> Preferences, then Advanced, followed by selecting the Show Develop menu in menu bar option.
See How to Clear the Cache in Safari [help.apple.com] if you need more help.
Clearing the browser cache from mobile Safari, like the one on your iPad or iPhone, is accomplished in a different app. From your device, open the Settings app and then find the Safari section. In there, scroll toward the bottom and tap Clear History and Website Data. Tap Clear History and Data to confirm.