The last one looks like a variegated pittosporum. It is a common hedge plant. It does need frequent pruning. Follow the basic pruning rules. Do not take off more than 1/3 of the plant at a time. Do the pruning just before the plant is to flush with new growth and feed it well just before pruning so it will have the energy to grow.
If it is pittosporum, I think the plants will take hard pruning but to be safe sometimes I will only cut back half the plant and wait for the new growth to start and then cut back the other side. It does grow back unevenly, but I can later prune to shape.
If you are not sure what it is, then prune it back slowly usually in the Spring just before new growth flushes. I would only cut back partially. If the plants are very old, they may not be able to come back well and may need to be replaced. Feed the plants before you prune.
Happy gardening in Hawaii. Gardens are where people grow.