First they make it impossible for you to find any information about this so i have copyed and pasted the page below the only number i could find that works
You can find the page here.
Regularly checking your credit report for changes you did not make is one of the best ways to combat identity theft. Your Equifax Credit Report™ helps you understand your credit report and what aspects lenders use to make a credit decision. Our expert customer service advisors are on hand to assist you with any questions you may have while your Equifax Credit Report is active.
The safety of your personal information is our number one priority. With this in mind, it's important for us to verify your details over the phone if you need to cancel, amend or upgrade your subscription.
If you wish to cancel you can do so through by contacting our customer care team, by phone.
You can reach our customer services team on 0844 335 0550, choosing option 3, between the hours of 8am to 8pm, Monday to Sunday.
Make sure you have all the following from your account see image below
Also another option email them at Member.Benefits@equifax.com
I got the following response
This e-mail confirms your request to cancel your Equifax Free Credit Report™.
We regret that you have cancelled your Equifax product with us, but hope that we will be able to serve you again soon.
You can view our Frequently Asked Questions at
http://www.equifax.co.uk/help , or you may wish to submit a question to us at
http://www.equifax.co.uk/ask. Alternatively you may contact us at 0844 335 0550 (Calls will be charged at 5p per min from a BT landline, charges from other networks may vary and from mobile phones cost significantly more), between 8am to 8pm, 7 days a week.
Thank you for your business.
Your Equifax Customer Care Team
We kindly ask that you do NOT REPLY to this email.