If you need to clear the cache and data of the Facebook app in order to fix certain issues with the app. This is how you do it: For Android users: 1- Open the Settings app. 2- Tap on Apps (scroll down to find it). 3- In the list of installed apps on your device, locate and click Facebook. 4- Tap on Storage now. 5- Finally, press the Clear data and Clear cache buttons. For iOS users: 1-On your iPhone, open the Settings app. 2- Tap on General, then on iPhone Storage. 3- Locate and tap on Facebook from the list of apps. 4- Finally, click the Offload App button.