How to clear all keys of all objects and bone? Is there any way to clear or delete all the key frames of all object and bones? 

I created an animation, but now I only want the model and not the animation. Selecting each bone and deleting every key frame is very tiresome job. I tried selecting all object and pressing alt I, but somehow the key frames still come back when I select a single bone.
Using scripts

Often for repetitive (&amp; tedious) tasks it is handy to use a small script.  

Remove all actions in file

Keyframed animation data is stored in an action. To completely remove all keyframed animation data, can remove all actions in the file.

import bpy
for a in bpy.data.actions:
    bpy.data.actions.remove(a)


Clear all animation data on scene and scene objects

To remove animation (actions, NLA, drivers) from scene objects and scene, but keep the actions in file.

import bpy
scene = bpy.context.scene
scene.animation_data_clear()
for o in scene.objects:
    o.animation_data_clear()