WTH said Cole was to "pursue other interests" and that his last day would be on Friday, March 23.
Cole founded Cruise118 in 2008 and entered into a partnership with WTH in 2010.
WTH said in a statement: "Since that time, he [Cole] has contributed greatly to the growth of the business and under his leadership, Six Star Cruises and River Voyages were launched, and WTH UK has become one of the UK’s fastest growing retailers."
Product and commercial director Earnshaw has been appointed managing director and "looks forward to building on the business’s achievements".
