You’ll need to create another project in your Control area and move the droplet there. From there you should be able to configure another VPC.
If you are not sure exactly how that works, I’ll recommend going over the VPS documentation on creating one and moving it to another project:
You can’t migrate Droplets between VPC networks directly, but you can recreate a Droplet using a snapshot. Snapshots are on-demand images of Droplets. You can create new Droplets based on snapshots to create a copy of it in the same state.
To migrate a Droplet to a different VPC network, from the control panel, click Droplets in the main menu. In the list of Droplets, click the name of Droplet that you want to migrate.
You can power off a Droplet through the control panel or from the command line. We recommend the command line because it ensures all services are stopped before the Droplet is powered off.