6. The Authority must delete from the Register any SROC which–
(a)has been revoked by it;
(b)has been produced to it under article 5(2);
(c)is no longer eligible to be produced to it under article 5(2);
(d)it is asked to delete from the Register by the registered holder of the SROC; or
(e)has been (according to the Northern Ireland authority) produced to the Northern Ireland authority by a Northern Ireland supplier under a NIRO Order,
and where a SROC is so deleted, it cannot thereafter be produced to the Authority under article 5(2).