[gerrit] Impossible to delete some of the ancient changes

[Mike Banon]

i.e. would like to remove the worthless & abandoned 17439 , 17505 ,
17506 , 17507 changes I have done at 2016 year (this work has been
eventually merged, so nothing of a value will be lost) - but a Delete
button for them is not available.

Best regards,
Mike Banon