I am really tired about how could i remove the unused tracks or delete them. I am not able to select all the unused tracks. How to select and delete them.
Don't have 2016, but you should be able to go to the mixer, highlight the track by clicking in the small space at the top, hold down Shift, click the last track that you want to delete, right-cick, Inser/delete tracks, Delete track(s). Or you can simply right-click on a track and delete it.
You can do it in the Arranger by clicking on the track number and then using Ctrl or Shift to select multiple tracks, then from top menu, Track, Delete track.
But It's also very easy to click on M, drag it out to see the tracks, and select multiple tracks. You can even rearrange the tracks here. Simply drag the select tracks left or right. I have 2 monitors, so the mixer is almost always on.
You can name the tracks, colour the tracks, etc. Lot's to learn and play with.