Device in list, but not found

I have a Device listed in Applications, if I click on the Button (with the device name) the message device not found comes up and I have no chance to modify or delete it. Any hints?
BR

from the command line ?

ttnctl devices can be used to manage devices.

  --app-eui string   The app EUI to use
  --app-id string    The app ID to use

ttnctl devices delete

ttnctl devices delete can be used to delete a device.

Usage: ttnctl devices delete [Device ID]

Example
Copy

$ ttnctl devices delete test
INFO Using Application AppID=test
Are you sure you want to delete device test from application test?

yes
INFO Discovering Handler…
INFO Connecting with Handler…
INFO Deleted device AppID=test DevID=test

see - https://www.thethingsnetwork.org/docs/network/cli/api.html