Yes, it's possible to start over with a brand-new account. You don't need a second email address for this. And you can also choose to start over with an empty account, or take some (or all) music with you.
(Skip the following paragraph if you wan't to start over with an empty account)
If there is any music that you'd like to take with you to your new account, you'll need to make sure it's saved in a Playlist. Music in Your Library that you want to take with you, will need to be placed in a Playlist. This is easily done on a computer as you can drag all songs at once from one Playlist to the other. When you've done this, you'll save the Playlists containing the songs you want to keep. You can do this by right-clicking a Playlist, going to Share and then clicking Copy Spotify URI. Save this link somewhere as we'll need it soon.
No we will be closing your 'old' account. By doing this you will free-up your e-mail address.
When you are ready with this, you can head over here and create a new account. Go through the process and log into the Spotify app. You'll have a brand new account with the same e-mail address!
Now is the time if you'd like to import your old songs. Paste the link you copied earlier in the search bar and open the Playlist you saved. From here you can place all these songs into one of your own Playlists or into Your Library on the new account.