Can I delete aut-num object from RIPE DB if it registered by me
(as LIR) for one of our customers and I have NO auth info refered by
object's mnt-by field?
I think you can't.
So if you need to keep control on objects - keep your mnt-by there.
Even then the ASN/PI is assigned to his customer, not to him. Unless
he's being authorized by the "gone customer" to delete that stuff (and
tell RIPE about it, otherwise it's probably a "weird state"), he's
doing something "illegal" (to the system). It's not his ASN/PI, it's
the customer's. No matter thru which LIR the requests where tunneled.
Can NCC folks confirm/correct this view?
You're right in stating that AS Numbers and PI ranges are assigned to
end users rather than to the LIRs that request them.