subscription

If you have a Photography plan, that plan does not exist as a monthly plan. But it's highly discounted, so you will not gain much by cancelling. What you can do is paying upfront for a year, and you will get even a higher reduction. 

Cancelling an annual plan will get you to pay early cancellation fees of half of the remaining due. You will need really to calculate your gain then. If you have a Lightroom plan (not the Lightroom Classic plan), you will in addition use cloud space. You can't cancel that, without saving your cloud data locally. It can be a laborious operation to restore that afterwards. It simply does not make sense.

if it's monthly you can cancel and start a new subscription as needed.  if you have an annual subscription there are things to be aware of.

make sure you're aware of the cancellation terms by selecting your plan type (at the top of the page here), https://helpx.adobe.com/manage-account/using/creative-cloud-subscription-terms.html

for info on how to cancel your subscription, this page describes the few steps involved, https://helpx.adobe.com/manage-account/using/cancel-subscription.html

if you want to cancel but are unable to follow the steps described in the "how to cancel page", contact adobe support by using a browser that allows popups and cookies, contact adobe support by clicking here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
be patient, it can take quite a while to reach a human
inform the agent that you want to cancel.