Unlock an iphone 5c that is icloud locked?

Hi

You are describing Activation Lock, which prevents unauthorised use of the iPhone if it is lost or stolen.

This can be disabled only by the previous owner (who may not be the seller) either entering their Apple ID and password on the device or by them removing the iPhone from their devices list in Find My iPhone via iCloud.com.

If you cannot arrange for either of these steps to be taken, then you will be unable to use the iPhone and should, if possible, return it for a refund.

There is no way around this security feature.

Apple will not advise you of the previous owner's contact details, nor will Apple pass your details on to them.

More information:

Turn off Find My iPhone Activation Lock - Apple Support

Only with the assistance of the previous owner, otherwise no.

I do not know my user name or password