The following nonconforming signs shall be terminated immediately upon the occurrence of the event specified:
(A) A sign that, having been permitted under previous regulations, is required to be removed because the sign, or a substantial part of it, is blown down or otherwise destroyed or dismantled for any purpose other than maintenance operations or for changing the letters, symbols or other matter on the sign;
(B) A nonconforming sign that has been abandoned;
(C) A nonconforming sign for a business or commercial enterprise that has been discontinued for a continuous period of 90 days; or
(D) A nonconforming sign that has become obsolete or substandard under any applicable ordinance of the municipality to the extent that the sign becomes a hazard or danger.