Just did this myself, and now sharing for others!
I have ChatGPT Plus, and when I tried to cancel it offered me a free month. Worked for two of my friends as well.
Steps
- Go to chatgpt on your web browser
- At the bottom left click on your name (you need to be logged in)
- Click on Settings
- Click on last section: Account
- Near top right click on: Manage
- Click on: Cancel Subscription
- profit