Till, heavily involved in the film industry, joined the board 12 months ago but has recently landed a new role based in the US which would restrict his involvement at Roots Hall.
In a statement on Southend's official website, Till wrote: "I have just been appointed as chief executive of Sonar Entertainment, a major American television company, and as their head office is in New York, for the foreseeable future I will be spending the majority of my time on the other side of the Atlantic.
"This makes it impossible for me to offer any ongoing, meaningful contribution to Southend United Football Club. For that reason I have to resign from the board, although I will still be coming to games and staying in touch with Ron Martin (chairman).
"I wish the club the very best of luck, not only in the current attempt to achieve promotion but also in the seasons ahead.
"Southend is a great club with a fantastic set of fans, some exceptionally talented players, a very impressive manager and a supportive board and all of you deserve huge success."
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