So. I was wonder if there is any way to draw line from top-view through extruded model. So basicly I want to make a cut with the line straight through
There is really no “top view,” just looking at a 3D scene from some angle–in this case straight above. What is seen as a line could be a face seen edge-on that cuts down through the model, and that’s exactly what you need. So draw a face (could be a rectangle, a circle, or just some closed shape with all of its points on a single plane) such that it passes straight down through the model where you want it cut. Then invoke the Intersect Faces command so the face actually cuts the model. Then, finally, remove the left-over geometry with the Eraser and Select/Delete.
NB: The simplicity of this description may be complicated by considerations of context, which you haven’t mentioned. If you have nested groups and components, this will require some more explanation.
People often overlook the native Section Plane for this sort of thing.
If you need this function a lot and prefer a one-click-solution, you can have a look at the plugin ($):