I assumed you are a postpaid customer.

If he is the account holder, he is the owner of your phone line. If you would like to move away, you would have to ask him permission first and do a Transfer of Ownership https://www.koodomobile.com/en/help/transfer-of-ownership-town

I am the owner and everything. As I said in my message I am the benefactor. He is simply a manager as it said in the selfserve.

Well, could you download the PDF bill in selfserve? and could you check the bill and see who name was on it?

If it was you, you can schedule a  call back from Koodo and ask for cancellation of his number. If it was someone else, you wouldn’t be able to do anything but following my suggestion above.

If the person you are the benefactor of is not willing to go through the transfer of ownership process as Dinh shared the link of, then you might have to cancel the line. I’d suggest, in case the person is not willing, to say they have only x time (your choice) until you simply cancel the line entirely. Hopefully it doesn’t come to that. If they have affordability issues with that current plan, they may have to look at cheaper plan options or prepaid with Public or Freedom if it works where you are located.