On Safari
On your Mac, open Safari and then click "Safari" in the top tooling bar. Click "Clear History" and select the timeframe from the dropdown menu. To delete your full history, select "All history".
On your iPhone, go into Settings and then click "Safari". Scroll down and click "Clear history and website data". Then go into "Advanced" at the bottom of the page, click "Website Data" then "Remove all website data".
On Google Chrome
Open Chrome and click on the three verticle dots in the top right corner of the window. Then click "More tools" and then "Clearing browsing data". You will be able to select the timeframe you would like to delete, or you can select "All time" to clear everything. Make sure you have selected "Browsing history", "Cookies and other site data" and "Cached images and files".
In an app on iPhone
Open Settings, go to "General" and then "iPhone storage". Scroll down to the app in question and click "Offload app".
In an app on Android
Open Settings and go to "App manager". Scroll down to the app in question and tap "Clear cache". Depending on your specific Android device, "App manager" may be called something different, such as "Apps".