FriendFilter does not automatically select who to unfriend.
You need to select from your inactive list who to remove as a friend
Then select the friends that you would like to unfriend
On Mac: Use COMMAND and click to select a few or SHIFT and click to select many
On PC: Use CNTRL and click to select a few or SHIFT and click to select many
You can also change the page to show 100 friends on the list and click SELECT ALL
On the free trial account, you can remove up to 10 friends for free.
On the PRO account, you can remove up to 100 friends per day, up to 100 at a time.
If you hover over the 100 friend countdown, you can see when that will refresh to get a new 100.