Can I track a stolen iPhone using the serial number if Apple Account is removed?

Sorry, no.

Your iPhone's Serial Number is only used for identification purposes, it is not used for location tracking. The only way you can track your iPhone's location is by using the Find My service, but since you say the thief removed your iPhone from your Account, that is no longer an option.

Unfortunately, there is nothing else you can do now to recover the iPhone. Be sure to change your Apple Account password and remove any unknown trusted numbers and devices. If you ever get messages claiming to be from Apple that your iPhone has been found, those are most certainly a scam.

The endless abuse, fraud, scams, assaults, thievery, and worse, that would arise, were that feature available. Every device everywhere could be tracked, forever, and by anybody that happened to know the serial number.

I’m mildly surprised you still even have access to the associated Apple Account, given the reported breach. Time to re-lock the account, and all passwords, passcodes, and passkeys, while (if) you still can.

If you think your Apple Account has been compromised - Apple Support

You cannot track the phone, but you can report the theft to the police and to your carrier.

If the carrier blscklists the phone, no carrier who honors the blacklist will ever provide cellular service to the stolen phone again.