|It's just so frustrating that I have to start over every time I fall.
This achievement is rather difficult and is considered quite hard. Due to its hard difficulty, the power cell reward for this achievement is higher than most achievements. Infinite Mode level achievements are usually not affected by this and they still keep their 25-75 power cell rewards.
You can only do this in a select level in Infinite Mode.
To complete this achievement, you will need to dislodge two different sets of crumbling tiles without changing gravity. The catch is that the two crumbling tiles are on different sides than the ones with only regular tiles, meaning you will need to try and dislodge it by jumping into the bottom of the crumbling tiles.
The Bunny is good because of its hopping, so it will be able to crumble the tiles on the wall without jumping.
Another good choice is the Duplicator, as you can just get your clones to dislodge the crumbling tiles without the actual character being in any danger. That way, you don't have to risk falling into the void when you go back. However, be careful to not rotate the tunnel with your clones.
While it is possible to complete the achievement with most other characters, it is very hard to get it using the Student, Pastafarian, or the Child for different reasons. If you use the Student's special ability, it will count as changing gravity to the game no matter what. So, you will need to jump across large gaps without ever using it, which is very difficult. The Pastafarian's light bridge will interfere with the sides, so the area where you could originally jump into the crumbling tiles to dislodge them is gone. With the Child, the achievement is completely impossible. This is because he is unable to dislodge the tiles without jumping off them and thus without being on the same side as them.
Another way you can dislodge the crumbling tiles is by dislodging them from the outside of the tunnel. Go outside the tunnel and dislodge the crumbling tiles from the outside. After this, go back into the tunnel without changing sides and repeat. This will work for any character except for the Child and Pastafarian (To see why, go to A Breath of Fresh Nothing).