Hi do not delete all your devices. You will have more problems if you do that. Instead pop on to chat you can reach them by clicking contact at bottom of this link and then selecting chat.
http://help.nowtv.com/article/Managing-Devices they will be able to reset your limit so you can remove the 4th device and readd. Keep them on whilst you process the change.
Please take a moment to click thanks or marked as solution if this answered your question. I am a community contributor and pop on when I can.
