Since you’re out of the country, your best option would be to send a private message to Koodo via Facebook Messenger. A rep should be able to assist you with the cancellation.

https://www.facebook.com/Koodo

Were able to receive incoming calls while you were traveling? If you didn't, you cannot receive a call back from them to cancel.

If you would like to cancel while residing outside of Canada, you can contact them via Facebook/twitter messaging. Links are at the bottom of this forum webpage.

Depending on your situation, if you want to retain your number, you can port over to a voip service. You end up able to still use the number with a data connection of any kind and it costs zero or very little per month. But if you don’t care and want it cancelled, then it’s as above