Leaving a Pro Team is easy to do. 

Go to Your account and then Team settings.

Click on Leave team to be removed from the Team plan. If you change your mind, only the Team owner can add you back. You can also start a new team yourself. 

If you are the Team owner, you cannot leave a team. The Team owner can remove team members from the Team plan. 

More about Team plans: 

How to join a Team plan
​How to add team members to your Iconfinder Pro plan
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