Q.Ti tree has gotten huge
It has gotten huge (6′ high). Can I remove leaves growing from top to slow it down? Don’t know how I will get it out of the house if I ever need to…

You can safely trim back all stems to about 12 inches from the soil line.
New shoots will grow back from the cut line.
If the plant has multiple stems that need trimming.
Cut back all but 3 of the stems. Allow the trimmed areas to grow back before trimming back the remaining stems.
You can root the cut portions in a clear cup of water and propagate new Ti Tree plants!
https://www.gardeningknowhow.com/houseplants/ti-plant/growing-hawaiian-ti-plant-indoors.htm