I cant Disable Collider

Hello! Im begginer in Unity. My game is 2D . I have 3 Colliders 2D (Left, Mid and Right). Example: If player its on Right Line and press Left-Button the player go to Mid Line and stops here, if I press again Left-Button, the player go to Left Line.

How can I dissable de Mid Collider when player stops there and need move to left or right ??

I try codding this all day but i cant do it works (I see all forums but i have new version of unity ). I have Unity 5.6.0f3 !! Thanks you!

hi;
with this u can disable a collider;

        GetComponent<Collider2D>().enabled = false;