There are a few different apps eg BT TV , BT TV Purchases , BT Sport , Youvierw App .
I suspect you are referring to the BT TV app - is that correct ?
If so there is this help page which might be of use
Many thanks for the replay. Yes i do mean the BT TV app and it seems there was a issue with removing devices.
Fingers crossed it's all sorted. They deleted them there end, on my box it was showing no devices. I now just need to wait until the 1st February to add a new device. If it doesn't work I will come back to you.