Mr Gibbs had chaired the board for five years. He is to be replaced by Bill Falconer.
Last year he was dumped as executive director of Guinness Peat Group, which owns 36% of Tower.
At the time, GPG chair Sir Ron Brierley announced Gibbs had been dumped for a "serious breach of boardroom protocol" but Mr Gibbs said he was "fired for telling the truth" in a statement objecting to the investment company's plan to spin off its Australian assets.
GPG intends to sell its stake in Tower as part of its plans to shed all its assets, bar its biggest investment - the threadmaker, Coats.
Meanwhile, Tower expects its full year profit will be within analysts expectations of $22 - $28 million, and its general insurance arm to be profitable.
Tower is confident it will get catastrophe reinsurance, though premiums will be higher.
Mr Gibbs also stepped down as chairman of the GPG-controlled Turners and Growers earlier this year.