How to clear data from lost iphone?

Sorry to hear that you have lost your iPhone. 

To locate it in the Find My [Device] app, you must have activated the Find My app BEFORE the iPhone was lost. Here is some information on that app If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support.

Note that your lost iPhone must be able to make the connection to the internet via Wi-Fi or cellular connection so that it can mark its location and broadcast it.

Axel F.

Yes you can erase your iPhone. Please click on this link-->>If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support and the article will show you how to erase your iPhone. Make sure that you leave that iPhone in the list of devices under your Apple ID so that the thief or anyone else cannot use it.

Axel F.

Yes, if you had "Find My Phone" turned on.

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support