Encrypted Sony Z1 Compact stolen - will it be possible to reset and reinstall phone without PIN code?
Yes, it's possible to factory reset (wipe) the phone, and then it'll be like new. If you want to make sure the phone can't be used any more, you have to report the theft to the police and make sure to give them the IMEI of the phone. (It should be written on the box it came in, or possibly your carrier will know.) Then they will blacklist the IMEI so the phone won't work on any cell network.