Hello Pavel,
I am not sure I understand what you mean by the text above the chord. Do you mean the text that initially is entered using the Text box for a specific space in a measure then using the arrows it moves upwards? If so, Touch that space, Touch the Regular Chord box twice, then the text will show in the box (if not it might be the space to the left of it (then delete the text).
Or is it the alt chords (small chords above the main chords)? You will have to Touch the Regular Chord button (so it changes to Alt Chord).
Regular chord -> Alt Chord -> Text -> Regular chord ...
If this does not help, could you post a screenshot of what you are wanting to delete? Thanks.