Can't Cancel Subscription totally

Hi, ​@Jiamin!

I’m sorry to see you’ve had some frustration with managing billing and seats for your Professional plan. When you downgrade team members to Starter, their former seats are still available for the rest of the billing period. When renewal happens, unassigned seats are removed and future renewals will not include them. This means that for the current billing period, you’ll still need to pay for the seats since they can still be assigned to team members. Does that make sense?

While we can’t assist with account-specific billing issues here in the forum, you can submit a ticket to our support team regarding billing questions specific to your account.

But I don’t want my former seats to be kept.
What I need is just to upgrade existing seats and  you can charge the upgrade price diff?

Ahh ok, so you want to keep the same number of collaborators and just adjust their seat type, ​@Jiamin? You can manage user seats by clicking the Admin link on the left side of the file browser. Once there, go to the People tab, click on a person’s current seat in the Seat type column, then in the popup select and confirm the new seat. If you have some extra seats that you no longer need and are unassigned - like what I covered in my original reply - those will not be renewed for the following month. Make sense? 

I also recommend looking at the help article on managing billing on the Professional plan for additional information on seat changes.