This data should be safe to delete. The most critical data in there are the asynchronous celery tasks, such as sending emails, exporting courses, etc. If you delete this data, then the tasks that were ordered but not yet triggered will never complete.
The permission issue stems from the fact that you deleted the redis data folder. It was re-created by docker-compose with root ownership. tutor local quickstart takes care of fixing the permissions.
I’m wondering if the issue is caused by the fact that you have such a large appendonly.aof file. If you have expertise with Redis, you can search for the configuration settings that will trigger a rewrite at the right time.