Pruning refers to the process of cutting small, specific sections of the plant to encourage healthy growth. At its most fundamental level, pruning removes growth that is damaged, unproductive, or blocking sunlight from reaching budding flowers.
You shouldn't have to do this much or at all. However, if you do see damaged leaves you may want to use the provided pruning shears to cut these specific sections of the plant. Please sterilize the shears before pruning to prevent pathogens from hitching a ride directly to your plant. The place where the plant has been pruned can be vulnerable to diseases or infections until it heals. Sharp shears are critical to making clean, swift snips that can heal quickly and don't cause undue damage to the plant.
Tu prune damaged leaves, make the cuts as clean and as close to the stem as possible, and at a 45-degree angle.
Here is a great video on how to trim, train and prune your plant.