You can leave any private project to which you've been added if you no longer need access to it. Here's how.
Tip- You can also leave a project from the sidebar by clicking the smaller v icon that appears as you hover your mouse over any project
If you are assigned tasks in the project, you have the option to reassign them to another organization member who is still a project member. Just type and select their name from the field and "suggested" dropdown.
Once you’ve left a project, the only way to regain access to it is to be re-invited by another project member with access.