Yes, retirement of any office or director requires an 8-K filing within four business days of the event.
However, there is no minimum requirement for the number of directors. In fact, the by-laws specify that the directors themselves decide on how many directors are needed:
"The number of directors shall be fixed from time to time exclusively pursuant to resolution adopted by a majority of the Corporation’s directors, but shall consist of not less than one nor more than seven directors . . ."
Most Delaware corporations don't specify a maximum number, and Delaware law requires at least one director so that is the absolute limit.
You may be confusing a by-law requirement with exchange requirements which generally require a majority of independent directors and specific compositions for the audit and compensation committees, but as far as I know the OTCBB doesn't enforce any corporate governance standards. In that case, one director would legally suffice.