Hi apple4L,
Welcome to Apple Support Communities. We see that you have concerns about your iCloud data being seen on a MacBook that was recently sold. We understand those concerns and would like to help.
From what you've described, your iCloud account is still showing this device because it was not originally signed out due to it not working. Since you're seeing it as Offline, we know that it's not currently connecting to the MacBook that recently had the hard drive replaced. This device will not be online again since it's not longer a complete computer. The only way it would be able to be wiped was if it connected to the internet. You mentioned that the other person was able to bypass iCloud. That can be done if they choose not to use iCloud when they set up the MacBook for use after the replacement. In order for your iCloud account to be on the device still, they would have needed to sign in with your Apple ID and password.
You mentioned that you don't have access to this account any longer and we want to help with that as well. Have you tried to reset your password? If not, follow these steps to get that done:
If you forgot your Apple ID password
Hope that helps!
