How do I make my character's walk animation stop when he jumps? I have this problem because, when my character jumps he reproduces the walking and jumping animation ends up giving an error, and in the end my character hangs in a position.

blender 2.79
This happens when you don't add any layer for the jump animation.
What's the meaning of layers in animations?
This is something like Photoshop projects, for example: layer1 is not appearing because there is another layer on top of it which is layer 2.
How can I add a layer or delete a layer in animation?
In the action actuator Here :

This is the layer what the animation is. In your case make the animation layer 2.
What about Deleting a layer?
You can't delete a layer. you can delete the actuator. You can just change the layer.