I know it's not possible to remove the storage fee from a V2 DAO (the contract can not be updated).
With a V3 DAO it should be possible to upgrade the DAO to a low storage contract that doesn't have any function besides sending the remaining funds to a wallet.
During the V2 to V3 upgrade there was a V2.2 which essentially deleted a DAO to recover the storage costs. This flow could be exposed via Astro in a similar way to how the upgrade flow works.
Some changes along these lines have also been explored at the smart contract level https://github.com/near-daos/sputnik-dao-contract/pull/63