Simple RAW for 5e V: The Disadvantage Strikes Back

[Chaos Jackal]

Q39: Can a creature slash through the wall of thorns created by a wall of thorns spell, and if so, can this be done without taking damage from the thorns?

Α39

If you're asking whether you can slash through wall of thorns in order to hit something on the other side, the answer should be no. It's 5ft thick and blocks line of sight. So even with a reach weapon you can't attack something on the other side.

If you're asking whether you can slash through the wall in order to destroy it, by RAW you can't. The wall has no hit points or AC, or anything that points to it being destructible (dispel magic notwithstanding). There's nothing about destroying it in its entry, unlike something like a Wall of Stone.