I did everything above, yet I still see this old computer on my account. When will it be removed?
when does an old computer I no longer own disappear from my list of devices on my iCloud?
MacBook Pro
Check your device list to see if there is a device signed in that you don't recognize. You can remove the device using the steps in the article below. As a precaution, change your password.
Apple ID device list -Check to see where you‘re signed in.
What to do after you change your Apple ID or password - Apple Support I suggest doing this before you change your Apple ID or password.