I’ve lost an iPhone without a passcode and had put it in lost mode at the moment. However, I would like to erase the data too as I do not want the thieves to see the contents on my phone. But when I press ”erase data” on Find iPhone，I was prompted for my iCloud password and phone passcode even though I had no passcode set. I suspect that the thief has probably set a passcode himself. How do I erase the data on my phone this way? Thanks.