When I work with other artists I'm often very stunned how many good ideas they dismiss and delete. Sometimes this happens because the artist is very experienced and knows that he can't use this idea in this song. But unfortuntely many artists, expecially unexperienced, tend to dismiss good ideas because they don't REALIZE that it were good ideas!
A very important factor during composition of a piece of music is to RECOGNIZE good ideas and to be open to new ideas!
Many young artists are desperate because they think they are not able to create the art they want. "want"!? This is exactly the problem. An artist has to realize, that he has to create the art he "can"! The "want" includes expections, expections include prejustice and this leads to an artists not being open to the art and ideas which actually knock on his door.
So when it comes to "keep" or "dismiss" decisions while composing keep in mind that you maybe have just found a good idea but have not realized it yet! Keep the elements you create even if they sound "weird" at first. Keep them even if you may have objections they may suddenly, in the right context or mood turn out to be the best ideas in your life!
Musical ideas, parts, melodies etc. etc. sometimes only reveal their beauty after time, in the right context, in the right mood. Just think about this: You often don't like good songs at first. Often you have to get to know a song, maybe hear it at a party or in your car or whatever. Now, this is no different in composing! Give yourself, your ideas a chance, let them live, let them be, let them develop, it's worth it!