I'm presuming you have the download version?
They can't really deactivate a license they've given you already, so basically you're asking for an additional license.
They might do it for you but, very reasonably, they might say you should buy a second license for that second computer since they're not the ones who made you pick the wrong computer the first time. Fair enough?
If you have the CD version you can install on as many computers as you want, of course.