There should have been a ReadMe file explaining that and you are not the first to make the goof, so let's see if this will help
Right-click on Start and select
Apps and Features. In that window, near the upper right, click on
Programs and Features. Give this next window a minute to populate the list, then scroll down to
Avid Pro Tools. If its there, follow these steps(if its not there, skip to
B)
Right-click on Avid Pro Tools and select
Change.
In the next Window, check the box to Remove Pro Tools and the HD Driver
Follow prompts to finish before running the new installer.
B
If you did NOT see Avid Pro Tools on the list, look for
Avid HD Driver (64)
Right-click on that and select
Uninstall
For future reference, while you probably don't need to uninstall before every update, DO uninstall before any update of a significant version number like this(and always look for a Read Me file)