The party's National Executive met immediately after the vote and after about 15 minutes announced that Gerard Batten would be the interim leader. There is no point in pretending it is not.
Two senior members of Ukip, deputy leader Margot Parker and the party's immigration spokesman John Bickley, quit the party after Bolton refused to step aside last month.
Mr Etheridge says he will be arriving early at the venue to hand out letters explaining "exactly why Bolton needs to go".
The former army officer's fate was decided after 63% voted to back a no confidence motion at an extraordinary general meeting in Birmingham.
"It may be too late to save UKIP, but you never know".
However, Bolton vowed to continue as party leader, despite the no-confidence vote.
UKIP, the United Kingdom Independence Party, was established more than 24 years ago to campaign for Britain to leave the European Union.
Mr Bolton, who lives in Folkestone, faced criticism over the relationship which attracted even more attention when it emerged she had posted racist comments and said the Royal Family would be tainted by Prince Harry's marriage to Meghan Markle.
Mr Bolton had further angered the party faithful by keeping in touch with Miss Marney, and bizarrely claimed he had been hounded like Princess Diana.
Since then, it has struggled to maintain its prominence and failed to win any Parliament seats during an election past year.
Mr Bolton, a former Liberal Democrat parliamentary candidate who defected to UKIP in 2014, has been at war with the NEC nearly since he took over.
The cash-strapped party faces a series of challenges, including the prospect of a hefty legal bill over a defamation action brought by Rotherham's three Labour MPs against MEP Jane Collins.
Former leader Farage recently described the party as "collapsing".
While waiting for the decision by his party Saturday at a UKIP meeting in Birmingham, Bolton told reporters, "It's not whether I go, specifically".
Writing in the Daily Telegraph, he says: "The basic structures of the party organisation are disappearing; branches are closing; and numerous sitting councillors in the forthcoming Spring elections wish to run as independents".