Now: deploy, alias latest and remove old deployments

now.json

{
  "name": "app-name",
  "alias": "app-name.now.sh"
}

now.sh

# THIS COMMAND SHOULD ONLY BE USED IF YOU DON'T CARE ABOUT KEEPING OLD DEPLOYMENTS
#
# Now: deploy, alias latest and remove old deployments
#
# "--safe" keeps the latest deployment and removes the rest,
# "-y" is shorthand for "--yes" which skips the confirmation dialog
now --public && now alias && now rm YOUR_APP_NAME --safe -y

package.json

{
  "scripts": {
    "deploy": "now --public && now alias && now rm YOUR_APP_NAME --safe -y"
  }
}