When in the things list at the top right there is a Select. Click that and pick the item you want to delete and the option to delete will appear at the bottom.
@timl you can attempt to delete it a second time and you will be prompted to force the deletion because the binding may become unstable. In this case its fine since you no longer want the thing
Thanks. Via list view it was not possible. I opened the Thing and got the error “Cannot load thing-type ‘mybmw:account’: Not Found” (Thw binding was uninstalled a few weeks ago). But the remove button in the Thing detail worked after the thing was in “Removing” state. Thanks.