If you paid for your membership via PayPal, login to your PayPal account and cancel the recurring payment. If you paid with a credit card, login to Creatrix and go to "My Membership/Manage My Membership" on the Members Only dropdown menu. Under your subscription listing, on the right-hand side, you will see the word "More" with a down-pointing arrow. Click this. You will see "If you want to cancel this subscription, please click here: Cancel." Go ahead and click on "Cancel."
Cancelling your subscription means that you will no longer be automatically charged each month. You will retain access to the site until the next billing date. After that date, you will no longer be able to login as a Creatrix. Your biography (under Meet the Creatrices) will be removed from the site. You will have the option to keep your creations on the site, or you can have them temporarily or permanently removed. You will no longer be able to post on the site, but you will always be able to visit and comment on the other creations along with the rest of the public.
If you decide to return as a Creatrix at some point after cancelling, you can resubscribe with the same credentials and your biography/old posts can be reinstated (as long as you did not request to have them permanently removed).