To select, you can right-click on the particle object and choose particle to go into component mode. Then you can select individual particles.

To edit, select some particles as above, and then go to the menu: Window -> General Editors -> Component Editor, and choose the particle tab.

Deleting individual particles is a bit trickier. You can write an expression to set the lifespan of some particles to 0, then press play. They will disappear, at which point you can save the initial state. Maybe there's another way, I'm not sure.