The easiest way is to see if the Fitbit connect app is still on your mac.
If so, then...
- open the app.
- Select the app's preferences (in the menu bar)
- Unselect the box labeled "Startup & Display, Show menu bar icon".
The little icon should disappear from your screen once you unselect the box.
I gave the product to my son about 6 months ago, and only now have gotten around to removing the program from my menu bar.
Once you do this, you can toss the Fitbit connect app from your app folder.