How to remove a lock when accidentally selecting "don't trust"

I accidentally clicked "don't trust" one day. Now It won't give me the option and won't allow me access to my phone when I connect it to my 10.9.1 version macbook pro. Specifically in image capture, the device appears but an error window pop up reading "please unlock -name of iphone-"

My phone is out of space in a bad way and I'd love to clear it off.

How to remove a lock when accidentally selecting "don't trust"