Non resident status

Hello,
I have a client that left Canada in 2015 to attend Oxford University in England and has not returned to Canada. He is now planning on staying in Europe now that he is married. When he left Canada he had a small savings account that has since been closed. Is there any paperwork that needs to be sent to the CRA showing that he is no longer a resident of Canada? Now that he is no longer living in Canada does he have to do a tax return showing his British income?
Thank you

Has your client filed Canadian tax returns since 2015 or at least a 2015 return? Has CRA requested that he file a return? He may want to file a final return for 2015 (or amend his already filed 2015 return) to show the date he left Canada. The problem is that 2015 may not be the date that he is considered to have become a non-resident of Canada. That depends on his particular circumstances.

"He is now planning on staying in Europe "

So the intention to become a non tax resident of Canada was formed in May 2021.

So he has been reporting his world-wide income on his Canadian income tax returns for 2015, 2016, 2017, 2018, 2019, and 2020 already, and paying Canadian tax theron, because he already knew how to do that himself without asking for professional help?

But now he is unsure about how to file a 2021 tax emigration T1, so now he wants a professional CPA to assist him?