Is it correct to say "unsubscription"?

I'm a web developer and in our project we use the word unsubsription to talk about making someone no longer subscribed to our maling. I know we can use the "subscription" word to talk about someone's intention to subsribe to a mailing or something similar. Is there a word which has the opposite meaning? I tried to find unsubscription, but neither of the following dictionaries don't know that:

oxford

cambridge

macmillan

We (being in a similar/related line of work) rather use the following phrase:

Cancelling (someone's) subscription

Although the word unsubscribe can easily be used, unsubscription does not seem correct. At the very least I can say it is not commonly used in technical presentations/meetings.

Note: There are quite a few words (or a composition of words) which are used frequently in scholarly papers and scientific presentation which do not currently exist in any dictionary, therefore the fact you didn't find a definition does not necessarily mean the word is incorrect. At the current rapid pace of scientific research, the need for new words and phrases every day has risen, and scientists are not necessarily going to wait for someone to give them permission. Just skimming through papers and presentations you can see many words and phrase which are derived from current language but do not yet exist in any dictionary.

I would suggest naming the process "cancel subscription", and referring to it during the process as "[your] cancellation".

"Subscribe" describes the action of creating a subscription, hence "unsubscribe". However, as a subscription is a thing, you can't really have an "unsubscription". It would be like describing closing your bank account as "unaccounting".