Delete selected particles and their trajectories

Question

I have a (baked) particle cache, I can enter "Particle Edit" mode, but I can't seem to be able to delete selected particle trajectories. Can it be done? How?

Example

I've created a minimal example: there's an emission object and a "kill particles" collision object. A "dupli" object is added just for visibility.

Let's say I want to remove retroactively all the particles that aren't killed by the obstacle.

Attempts

Several other related questions have answers that mention Select+X and Select+Del (in Particle Edit mode) as ways to remove trajectories or trajectory points: it wasn't specified. I'm unable to do either.

In "Path" select mode, I can't seem to select anything, with either RMB or C+LMB:

In "Point" select mode, I'm able to select trajectory points (but I wouldn't know how to select all the trajectories: there's no Ctrl+L functionality). However, X and Select+Del show no effect.

Same for "Tip":

The "cut" brush also seems ineffective:

File

you can download my minimal example here:

Answer 1

Via a Frame change handler

Here is a frame change handler to set the size of any particle still alive at frame 27 (arbitrary choice from sample file) to zero. Needs to change frame to 27 at least once to set the list.

System console print from sample file

27 [5, 12, 15, 16, 18, 21]

states on frame 27 particles 5, 12 etc are still alive, and will be zeroed in size each and every frame from now on. Once this is known it could be hard-coded into the handler instead of calculated each time.

import bpy

context = bpy.context
ob = context.object
parts = []

def particle_remove(scene):
    global parts
    ob = scene.objects["Emits"]
    ps = ob.particle_systems.active
    for i in parts:
        ps.particles[i].size = 0
    if scene.frame_current == 27:

        parts = [i for i, p in enumerate(ps.particles)
                if p.alive_state.startswith('ALIVE')]
        print("27", parts)       
bpy.app.handlers.frame_change_post.append(particle_remove)

to remove the handler (and all frame change post handlers)

bpy.app.handlers.frame_change_post.clear()

Answer 2

As far as I know, there is no way of deleting individual particles.

BUT - possible workaround: In particle edit mode, deselect "Keep Root", hover your mouse over a strand, press L to select the whole strand (you'll have to repeat this for every single strand) and move them somewhere else. They'll still be in the scene, but out of the way at least.