The board may authorize the destruction or disposition of any record, paper, or document which is more than two years old and which was prepared or received in any manner other than pursuant to a state statute or county charter. The board may authorize the destruction or disposition of any record, paper or document which is more than two years old, which was prepared or received pursuant to state statute or county charter, and which is not expressly required by law to be filed and preserved if the board determines by four-fifths (45) vote that the retention of any such record, paper or document is no longer necessary or required for county purposes. Such records, papers or documents need not be photographed, reproduced or microfilmed prior to destruction and no copy thereof need be retained.