You can remove a song only if you are owner of that song and if you don’t have song Remixes. Tap on the song menu and select Remove button as shown here.
Piano Companion is flexible chord and scale dictionary with user libraries, reverse mode and a progression builder.
ChordIQ
ChordIQ
is a music-based mobile game focused on learning notes, guitar and piano chords in a fun and interactive way.
Songtive
Songtive is a songwriting tool, band and social network. Songtive helps to experiment with arrangements and chord progressions which is available for iOS/Android.