Project Permissions in Jira serve for fine tuning access to different parts and functions inside a project. You can only access these Permissions menu if you are a Project Administrator.
Go to Your project → Project settings on the sidebar → Permissions → Retrospective Permissions
Create Retrospective Event - lets the user(s) with this permission to create retrospective boards for the project and launch retrospective events from the Backlog. Only users with this permission can become Facilitators
Delete Retrospective - lets the user(s) with this permission to delete in progress or completed retrospective events from the Retrospective History
Join Retrospective - lets the user(s) with this permission to join in progress retrospective events
Edit Action Item - lets the user(s) with this permission to edit Action Items on the Dashboard