Can Find My Mac be disabled on a stolen MacBook without a password?

My friend had his MacBook stolen from his house but he didn't have a password on his MacBook so if the thief logged out of his iCloud can it still be tracked since he already put a lock on it?

If he deletes the iCloud account while the MacBook isn't connected to Wi-Fi can he still track it if the MacBook connects to Wi-Fi?

1. No, not without the original password
2. No, but you can sign into your icloud account from a different device and track the computer

Can Find My Mac be disabled on a stolen MacBook without a password?

Yes, it could be done also on MacBook with account password.

If you don't have configured a password to choose boot options the thief is able to delete all your content, without having your root password. He can simply:

1. Do not connect your Mac in internet.
2. Turn on Mac pressing Cmd+S to enter in CLI mode.
3. Change your admin account password (I have intentionally omitted details on this step).
4. Logout.
5. Login using your account with his password.
6. Disable all services related to iCloud, so disable Find My Mac.

In this case you're unable to locate your Mac and the thief is also able to reinstall from zero the Mac OS X.