Hi, @alanblaze, unfortunately you do not mention what system you are trying to use to do this. If it is your phone app, open the app and choose "account". It is the icon that is a small rectangle with a circle and some lines (I finally worked out it was meant to look like a photo ID)
On the account page scroll down to "set up a device" and follow the instructions there.
You can also click on your Flex and scroll down on the next page to choose to remove it, if you like.
Sense, Charge 5, Inspire 2; iOS and Android