If you are shackled by something, it prevents you from doing what you want to do.

If you throw off the shackles of something, you reject it or free yourself from it because it was preventing you from doing what you wanted to do.

Shackles are two metal rings joined by a chain which are fastened around someone's wrists or ankles in order to prevent them from moving or escaping.

To shackle someone means to put shackles on them.