Firstly, it's a Shefflera arboricola. Getting it to bush up isn't easy as their natural habit is to grow upwards. I always found that if you remove the growing tip, they would tend to send out just a single side shoot which would continue upwards as a new leader.

You can try taking out the growing tip, and then when any sideshoots grow, do the same to those but it might be a long process.

Good luck

I can't get my Shefflera to bush out at all. I cut the top off but it just sent out one side shoot, which continues to grow upwards.
If the base looks bare maybe you could cut it low down, and then it might look bushier when it grows a new shoot from there.

Everyone's right - these plants just grow straight up, but yours is a bit of a sorry state, frankly, it should have leaves more or less down to the bottom of the stems. The thing to do is cut it down, then remove about 8 inches off the top, strip off the lower leaves, pop them in a bottle of water on a windowsill and wait around 6 weeks, keeping the water topped up. When the roots have appeared and are long enough, pot them up. You don't have to do this, but if the original plant is very slow to regrow (and sometimes they are) then you can bin it and keep the new one, which will grow away strongly - but still upwards. Keeping it fed and watered but not saturated will enable it to keep the lower leaves as it grows, but you will need to stand it somewhere (like the floor) where it can easily grow upwards, and with sufficient light.

Scheffleras will grow more side shoots when they are well fed, and have plenty of light. Yours looks a bit starved for both light and nitrogen, Annee.