This expedition _ which has 37 team members including 27 from Nepal _ includes four Wanaka residents and six climbers from the United Kingdom, Japan, Australia, Ukraine and Iceland.
All expedition members were yesterday at Base Camp, where a service for the dead was held.
Mr Cotter said team members, along with the entire climbing community, were still ``in shock'' over the "enormity" of the avalanche.
They will spend the next month dismantling their camp and making their way down from Base Camp.
Mr Cotter plans to leave Nepal for New Zealand next week.
"Now a decision has been made it gives everybody the opportunity to get on with things and move forward. I think everybody was in a state of limbo, not knowing where things were going, and during the heat of it all there was a lot of emotion involved,'' he said.
At least one other expedition, by a United States company, has also been cancelled and others may be abandoned in the coming days.
Sherpas have threatened a strike unless promised greater government compensation for the families of those killed on Everest.
"There's a stand-down period for a week where nobody's going anywhere near the mountain. All the Sherpa teams are from the same village or related to some of the people who passed away so everybody is affected _ it goes through the whole community," Mr Cotter said.
Watch: Deadly avalanche sweeps slopes of Mt Everest
Adventure Consultants general manager Suze Kelly, of Wanaka, said the company was negotiating wages and compensation with its Sherpas and other Nepalese expedition members.
"It's been a very tough time for them as they're all in a state of shock and still grieving. We are looking after all our staff, and we need to be able to give them room to recover from the enormity of what's happened," she said.
The company would also try to reach the ``best outcome'' for the six climbers who had paid to be part of the expedition, Ms Kelly said.
"If we can do a partial refund, or a reduced cost for them to do the expedition next year, we'll try to do what we can. Like any mountain that you attempt to climb, the outcome is never certain and it's a difficult situation."