FAQ : Connectivity (Tunnels and Subnets) : My tunnel/subnet stays in deleted state
My tunnel/subnet stays in deleted state
Even though you have deleted your tunnel it stays in deleted state for historical reasons. It could have been hidden from the user interface but now you are remembered of the fact that you had a tunnel and/or subnet and that it is deleted. And indeed in that state it doesn't work anymore, it is only listed.
This also makes sure that even after someone has deleted his/her/its tunnel or subnet it is still possible to trace who owned the concerned prefix which can be quite useful in cases of abuse and or old systems that still use this old prefix.
PoPs in general are allocated a /40 worth of IPv6 address space. This block is chunked into 256x /48. The first /48 is in general used for tunnels, the other 255 blocks are used for subnets. When we either run out of tunnels or out of subnet blocks, the blocks that are marked for deletion are permanently returned to the free pool so that they can be used to satisfy new requests.