I purchased an iwatch tonight and it was not unpaired. Can I unpair it without the original owner and her phone?
No. The owner needs to remove the watch from her account, or you'll never be able to use the watch. Do you know and can reach who you bought the watch from? If yes, this is what they needed to do --> What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support
If you can't reach who you bought the watch from, you've purchased a useless wrist ornament, you can't use. Recycle it responsibly in that case.