If the link does not belong to your npub, then it would be impossible to delete. We only allow you to disassociate from the uploaded media if it is a duplicate, or delete the media if you own it. 

 I sure use the account which I uploaded the image delete the image. 

I know that 

 Please check that in the browser using the Developer Console and see the headers. We have x-owners-npub (or something like that) if it is properly authenticated when it was uploaded. 

 Thanks, will try and let you know when I am at home later