Ideas are relatively 'easy' to dispose of, but physical things are harder. I can't countenance throwing away something of value, so I have to find someone who will make use of the object, and then either give it away or sell it. It's a lot of work to find homes for the unwanted, so nowadays I just stop bringing physical things into my life if it can be avoided.
Agreed - when it comes to physical things, part of the whole idea of living a minimalist life is to reduce the intake in the first place. Rampant consumerism and convenience/disposable goods are the opposite to a minimalist ideology.
Putting value on a thing is an idea. If you couldn't dispose of physical things your house, it would be piled high with trash. You get things because you have an idea of how you want to use that thing ( I guess the ego could play into this as well.) Once you realize the idea for getting the thing was flawed, you can either iterate on that idea and try to find a way to continue using that thing, or admit that the idea was flawed and just remove both the idea and the thing.