How to unlock or restore an iPhone without updating it?

I recently purchased an iPhone 5s because it was running iOS 8 and I collect older iPhones. I bought it knowing it was locked with a forgotten password. I thought I would be able to wipe the device to unlock it since none of the data on the device is needed anymore, but each software I've tried to use (iTunes & Anyfix) would only let me Restore and Update the device when all I want to do is Restore it. Is there anything I can do to either wipe the device without updating it or somehow get into the iPhone to wipe it?