OK, so start w/ the easy part. I'm assuming since you mentioned all your dockers getting trashed, nothing needs backed up.
Delete your current emby container, delete the current /config folder you created, and if you're not using the linuxserver image... delete the image you're using. You can do all that in portainer. Then go ahead and create a new /config folder
containers & images gone. Can't delete my Config folder or its contents (Permission denied)