Take a look at the Usage Summary widget. It looks like this: This widget shows a count of used licenses vs. allocated licenses. Any disparity between these values means that you are paying for licenses that are not being used by your teams, so you'll want to identify which teams require adjustments. To do so, proceed to Step 2.
Compare the numbers in the User Licenses and the Used User Licenses columns. Do the same for the Server Licenses and Used Server Licenses columns. If they are not equal, the team has too many license allocated to it.
For each team in that situation, proceed to Step 3.