Easy.
In the block event, put a conditional branch checking which direction the player is facing. Then make the block move away.
Event: On player touch
Conditional branch
>IF player is looking left.
THEN move right.
>IF player is looking right.
THEN move left.
>IF player is looking up.
THEN move down.
>IF player is looking down.
THEN move up.
Not hard. You could also make it slide by doing-
>IF player is looking left
THEN move right, repeating until cannot.
ETC...