[v3d4]

when the plant is almost finished, it will draw out the resources stored in the leaves and they will turn yellow, so those yellow leaves are no longer needed you should remove them.
any leaf that is green and healthy looking and getting good light is working to make food for the plant, so dont cut it off.

leaves that are in the shade and not receiving good light might be taking a little more energy than they are making. so in a really dense bushy plant for example, the underneath and inside fan leaves are not really doing any good. better to remove them for good airflow so you dont get areas of high humidity that can invite a mold attack.

keep in mind that pruning the plant during flowering can slow down the bud growth if you chop a whole lot of stuff off at once, because the plant has to put some energy into healing all those little wounds. so any leaf removal should be either before flowering starts or shortly before harvest, and dont go crazy.