Doctor Jaeger

Hi everyone. I'm playing on single player. Don't know if that's reported yet, but after digging out the terrain for my base, there are still some left-over dirt blocks which I can't dig any more. I can stand on them, they are recognized by the hitbox, but my tools can't destroy them. They just hit the blocks behind or under them. Even digging up the space under those dirt blocks so they would collapse doesn't work. How can I get rid of them? P.S.: Is there an admin or dev tool where you can mark a box of blocks and delete them all at once? Like some creative tools mod in minecraft? Greetings, Doc