I hate abandoning writing projects, although up until two years ago, they were all I had. I keep all of my past material, jots of plot lines and snippets of scenes, in manila envelopes in a file crate (I keep my Heather Stokes material in a separate crate).
Every once in a while, I pick through them and try to remember where I was going or what was going on. I enjoy seeing how much I’ve matured as a writer, and every once in a while I think of a project I want to pull out and bring back to life. Since I kept that material, it is easier.
Do not throw away material.
I know several writers who regret throwing material away, but no one who regrets keeping it. Even if you hate it or hit a wall, don’t trash it. Tuck it away somewhere and forget about it. You might encounter something that makes the idea you had click in a way it hadn’t before, or makes you remember why you thought it was a great idea in the first place.
Do not throw your idea away. Pick it back up, dust it off, and use your more polished writing skills to finish it up.