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 Event - lets the user(s) with this permission to delete in progress or completed retrospective events from the Retrospective History
Join Retrospective Event - 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