It won't hurt anything. The only(almost) time I choose to cut a leaf off, is if I get paranoid,lol and think that there's a chance of it growing mold/fungus. Well, or if it's hanging close to, or in, the soil, for the same reason. Otherwise, I don't cut any. I wait until they are yellow,(for example) and fall off when I touch them. Those, are no longer in use, and are ready to go, obviously.LOL
There's other times when it's okay to cut or trim, but, I hate trying to explain 'when and why' to a new grower, because it's something I think you should learn for yourself, what works for you. Experiment a little, and you'll get a 'feel' for it. Just don't get too carried away, and it's tough to do any real damage. On my second grow, I got the bright idea to cut off the majority of large fan leaves near the top of the plant, during mid-flowering. Well, let me tell ya, those buds turned out airy as hell, and the plant never seemed to finish. It was a consistent 8-9 week strain, during all my other grows, always producing nice dense buds, so I know the trimming really messed it up. I knew right away, because I was watering every other day, before trimming, and every 4-5 days, after trimming. It definitely altered the metabolism of the plant,(the main risk of trimming leaves, IMO) and it never seemed to take off again. I put it into 'eternal slow motion'.LOL