Delete all keyframes in a specific time range

Is this possible? I have a Null with tracked position/rotation keyframes on it. Depending on the project, I don't want to use all the keyframes. So I delete the first 10 or so that I don't use.

Can a script delete e.g. all position keyframes before the layer's in-point (or before a specific layer's marker)?

Thanks in advance!

- Michael