I was using a monthly payment plan. but when I want to cancel, it asks me for a withdrawal fee. I was a monthly subscriber when I bought the subscription. Why am I being asked to pay for a service I don't use? I can't find any answer either.
More than likely what you signed up for was the annual plan paid in monthly increments. If so, you've agreed to subscribe for a full year and Adobe does charge a fee if you cancel before the year is finished. Some subscriptions allow you to subscribe month-to-month, but they're more expensive. You can see the differences for the All Apps plan highlighted in the graphic.