Replace Dm7, Db and Gm7 with F; Am7 with C. Simplify all chords to major or minor as indicated (ignore 7s) and ignore bass notes indicated for chords..
You're then playing in I, IV, V, (F, C, Bb) and G7.
Try it out, if it doesn't work, adjust the chord(s) that don't sound quite right, or just play the root note. Also, you can simplify the treble to a single line melody.
Good luck!