If you wish to deactivate an installation, click on My account from under your user icon in the top right when logged into and go to the Office apps section for links to sign out of a device. You can also run the Office Mobile Apps (Word, Excel, Powerpoint) on up to 5 mobile devices (on various platforms). You may run Office on up to 5 machines (Mac or PC).
Your UTmail+ account gives you access to full desktop and mobile versions of Microsoft Office to install on your personal devices.