Erasing iPhone 5S

I have just received a rebuilt 5S, which I was supplied to replace my 5C for work. The phone has had a new screen etc put on it but has not been erased. It has someone else's apple ID loaded on it and there is no real way of finding out who's, as it is rebuilt and I don't believe the apple ID is from anyone at work here .Is there any way of erasing this phone so I can load my backup to it and use it or do I need to send it back to our IT department. I was hoping not too as that will take another 3 days to get it back.

Thanks