I would like your advice on a 7ft tall Schefflera that has not been repotted in over 10 years, but has only 1 stem . The bottom half does not have leaves. Should it be root pruned and cut back a little, or repotted and make a tip cutting from top 12″ of stem ? The tip cutting would be started in same pot with parent plant.
Your Schefflera should NOT be repotted. It is not commonly understood that older plants that are grown indoors never need to be moved to a bigger pot, nor should they be root pruned unless necessity requires it to be moved to a smaller pot.
The height and age of your Schefflera are not related to the root size. The single stem adds new growth only at the top, so inevitably it gets taller and taller as it loses older leaves down below. The only solution to this is to prune it back. It is always better to prune well before it obviously needs to be pruned. You did not include a photo so I cannot tell how badly overgrown it is.
My educated guess is that at least the top foot should be pruned off. Remember, that the new growth will come in just below the pruning cut and grow upward from there. It won’t be that long before a foot of new growth will leave you in the same place you are now. Thus, it is best to prune back as much as you can stand. Remember also that pruning affects the appearance of the plant, but not its health.
The top section that you prune off can be rooted in the base of the plant. Dig a small hole large enough to insert the bottom 1-2 inches of stem and then tamp the soil around the cutting. You can also root it in its own separate small pot or air-layer it.