The Danes colonised England. They never left but merged with the existing population.

https://www.britannica.com/place/Danelaw

That involved a rather genocidal approach in 1065 - killing everyone related to, or doing business with the Vikings. This tends to get downplayed by historians. And when the Vikings/Norsemen came back for revenge in 1066, King Harold 2nd managed to kill off the Viking force at Stamford Bridge, but was too exhausted when William invaded down south (being defeated at Hastings). 300-ish miles is a short drive by car, but in an era long before preserved food or mechanized transport, such a march over about 2 weeks would have been terrible.

Overview: https://www.bbc.co.uk/history/ancient/vikings/overview_vikin...

https://en.wikipedia.org/wiki/Northumbrian_Revolt_of_1065

https://en.wikipedia.org/wiki/Battle_of_Stamford_Bridge

https://en.wikipedia.org/wiki/Battle_of_Hastings

No they didn't. The vikings became part of the population