You mean this one?
You can't but it should stay away once dismissed until the next reboot. It's a little less obtrusive on beta versions of the software so maybe you'll get you wish soon once the software upgrades.
You could always start a quick scan then immediately cancel it, that would stop it for a while I would imagine.
I never run a scan unless I need to so I see it here all the time. You get used to it.
Unfortunately those sorts of things rarely get much attention but you could try putting in a product improvement suggestion here: https://community.mcafee.com/community/home/ideas