delete keyframes

I tried to animate a model and I used following lines to insert the keyframes:

This code works fine and I get a good animation!

Now I like to delete all the key frames from within the python code.
I can delete them manually in the Action Screen, but not with python scripting.

Any body a suggestion?

Is it maybe possible to delete the Action and all the keyframes?
I just have to delete the stored keyframes. Manually it works in the NLA screen, but it has to be with python scripting.