So you don't want the mail to be downloaded on the Mac notebook? If so that is an odd request from the usual posts on any forum.
Usually people ask how can I get my mail on all my devices. Not how can I stop mail from being downloaded on X device.
The simple asnswer is Delete that account on that device you don't want the mail to downloaded to.
You'll need to make a text or word processing file of all the settings for that account, which is what you should do anyway so you can always refer to it if there are problems with any device.
The suggestion above may work but more then likely that will also delete that account, at least some of the setting for that account.
My suggestion will work fine. I just tried it and it does not delete settings or mail. He stated he wants to keep the settings available on the machine and this will do it. It will also remove the mailbox until it is rechecked again. Yes, perhaps he should keep a text file of the settings (that is good practice) but unchecking this box will not permanently delete anything.