We currently do not offer a single-click way to do a downgrade. If you are looking to change your Team account to a Solo account, the easiest way to downgrade your account is to turn off the auto-renew on your subscription, and then let your subscription reset to a free Basic account when your current subscription runs out. Once you have downgraded your account, you will be able to purchase a new subscription for the account plan of your choice.
All of the information that you had as a paid account will still be in your account once you have re-purchased your account as a Solo plan. However, this will not include information that belonged to or was created in an account that belonged to one of your Team Members.
If you are looking to downgrade your account from a paid account to a free Basic account, all you need to do is cancel your subscription in your Account Settings.