quit_sub: TxDescriptor<undefined>

Remove the sender as a sub-account.

Payment: Balance reserved by a previous set_subs call for one sub will be repatriated to the sender (not the original depositor).

The dispatch origin for this call must be Signed and the sender must have a registered super-identity.

NOTE: This should not normally be used, but is provided in the case that the non- controller of an account is maliciously registered as a sub-account.