su root not working

Hi

I tried to create a droplet, I went with the default settings, I picked an SSH key.

I then logged into it fine with the SSH key I picked.

I then created a new user.

$adduser bob<ENTER>

$su bob<ENTER>

That was fine.

But now I can’t $su root

If I try blank password it won’t let me. And I didn’t set a password for root. I only did default settings.

How am I meant to do it?

Thanks