Add this option inside your billing page or subscription plan page, do not show it separately in the menu where user can see it every time site visit. Because users may attempt if they find it easily. The right place or standard place for the cancel subscription is billing page/plan page/subscription page/my dashboard page. Do not add it in the menu.
This is my highly recommended option; it is very powerful and beneficial for website owners.
Suggest few options and provide facility to tick mark them. Feedback is very important to improve your product/services.
If users use your product or services for short time then it will help you to get some good reviews/ratings/testimonials which you can use them as trust indicator in your website.
Give option to change their plan or lower plan
This is a good idea to motivate them again.
Provide here Live chat, email and toll free no. so users can share their problem about the website and you easily resolve them and get beck your users to in.
Some users do not want to use your product or services regularly so it will help them to off auto detection of money. Must do A/B testing for this option because you may loss profit.
It can also help you to reduce cancellation
This technique can help you to get back your customers.
If they allow you for getting notification you can approach them with discount offer and inform them for addition features in future.
FAQ can help your customers to resolve their product related query.
Say thanks to your customers for positive impression.
If user not ask for account deletion, do not delete it and if user will come in future not need to re sign up.