Exchange 2013 Activesync device issue

I have a strange issue, one of my user registered 2 ActiveSync devices in exchange for syncing mails, now he is not using one of the device so we tried to remove it through ECP but couldn't succeed (error the device could not be found) so we tried removing it through ADSIEDT and removed the device, but the same device is still visible in ECP device list under user properties, while check it through the exchange PowerShell it displays only one active device.

how can we remove the device from ECP, tried several times through ECP but getting same error that" the device MOWA§iPhone§14168884968490015481077134609222 cannot be found"

Help is highly appreciated.

Thanks,

Imran