Disposing of old written notes Many a times, I study some topic or research paper and make my own notes (it could be figuring out the math in paper, or something else). But after say 7-8 months, these notes just pile up on table and when I look at them I don't think I will be using them for any future work. But I also feel like I'm trashing my study, and the effort was pointless if I dispose of it. Is it okay to dispose of them? What strategy do you have about disposing of written notes?
It may help you to understand that much of the value of those notes has been the very act of writing them.  As such, you may find that you have less compunction against throwing them out.  

Personally, I maintain an "aging pile" for notes, in which I keep them until they stop feeling relevant.  For some things, that's a week; for others it was a box in my closet and a decade.  You can also remove the physical clutter aspect by scanning and archiving in something with cloud storage: you'll be trading physical clutter for electronic clutter, but I at least find that electronic clutter is much easier to ignore.