How to decelerate the player with a force on it?

Hi all!
I added a force to move the player towards the left side of the screen when pressing “A” like this:

How would I smoothly decelerate the force when he releases the “A” Button until the player stops?

Make there a hidden object and set when you release the “A” button changes the position of the hidden object to a point inside the player then set it when the hidden object collides with the player set speed to eg 10, and set it also when you press the “A” button the hidden object moves to another position you specify.
or you can inverse the condition for “A” button then add other force for player

I’m not at my PC. Could you apply a smaller force in the oppsite direction (+/- 180°) until the movement is at or near zero and then stop all motion?