Trimming sago palms can be very tricky: people tend to overuse pruning when dealing with sago palms, especially because they are rather unsightly when their leaves begin to yellow and die. However, you can't cut something away and expect it to fix everything; you must first understand why it turned yellow in the first place. Sago palms will show this type of damage when there is lack of nutrition in their soil. By cutting away the dying palm, you can actually do more harm than good to your plant.
To reduce the chances of your palms turning yellow, you should fertilize once every six weeks, as this well help to eliminate any deficiencies in the soil. You can also apply Epsom salts to the soil to help rejuvenate the plant. There are many different methods you could use to help correct the unattractiveness of its decaying palms.
If, however, the palm is too far gone and is completely dead, you can trim it away. Trimming should never be excessive and it should be one of the last things you do to correct the look of your plant. When pruning and trimming sago trees, not only does it decrease growth and development, but it will also make the plant more susceptible to diseases and pest infestations.
When you notice that the plant is looking run down and ragged, or there is discoloration marring the look of your plant, the best thing you can do is analyze the problem and figure out why it's happening. Chances are you will have a better turnout approaching it in this way then if you were to simply take the shears to its foliage and fruit. When there is no other option but trimming, be sure to cut the oldest leaves closest to the base of the trunk.