Trim in flower?

Yeah mate, you can totally take leaves off the plant in flower. Typically defoliation in flower takes two forms, the first being lollipopping and the second being defoliation. Lollipopping is taking off both leaves and branches off the bottom 50% of the plant. The goal being to get rid of bud sites that don't get enough light and redirect the plants energy into producing bigger buds at the top. You typically want to lollipop latest 2-3 weeks into flower. Defoliation is just taking off some of the leaves towards the top of the canopy that are blocking light from lower budsites. Don't take too much off, or you'll stress your plant. I suggest you attempt to tuck the leaves beneath the budsites before you defoliate. If you can't tuck them, then simply remove them.