Help authorizing my PC for my Adobe ID

I am trying to authorize my PC for my Adobe ID but it notes:

"You can only authorize this computer with an Adobe ID that hasn't been previously used to authorize any other computer or mobile device. Please try again"

I purchased an ebook but realized I needed IT approval to have ADE on my PC. While I waited, I authorized my mobile device with my Adobe ID.

I just got IT approval to download ADE on my PC. When I tried to log in with my Adobe ID and sync my ebook, I got the error above.

I thought I should be able to read this ebook on multiple devices.

Can I deauthorize my mobile device so I can authorize my PC and my ebook still who up on the PC?