composer create-project symfony/framework-standard-edition appname
cd appname
rm -rf app/logs/* app/cache/*
chmod 777 app/logs && chmod 777 app/cache
rm -rf src/Acme
Then delete Acme' references into:
app/config/routing_dev.yml
app/AppKernel.yml
web/bundles/acmedemo
php app/console generate:bundle --namespace=ReadItLater/MainBundle --format=yml
Don't forget to rename the bundle via the generator