If you've been invited to an invite-only project, you have the option to leave it any time. To do so, open the project you want to leave, click
v beside the project name, and select "Leave project" from the menu that appears.
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 teammate who is still a project member. Just type and select their name from the field and "suggested" dropdown.
When you're ready to finalize this decision, click "Leave."
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.