iPhone
To clear the Safari cache on an iPhone, go to Settings > Safari > Clear History and Website Data. Alternatively, to clear only the cache without history, go to Settings > Safari > Advanced > Website Data > Remove All Website Data.
Android
To clear the browser cache on Android, open the Chrome browser, tap the three-dot menu, and go to History > Clear browsing data. In the "Clear browsing data" menu, select your desired time range (such as "All time") and make sure "Cached images and files" is checked, then tap Clear data.