You need to change the root password for the droplet.
You can change the root password for the droplet from your DigitalOcean account.
Navigate to the control panel. From the project the Droplet is in, or from the main navigation’s Droplets page, locate the Droplet. Click the Droplet’s name to open its detail page, then select Access in the left navigation.
Click Reset Root Password to send an email to the address associated with your DigitalOcean account. You can use the password provided to log in to your Droplet through the console.
You can also check our official documentation about this:
Hope that this helps!