Looking for suggestions on how I should trim and prune this to bring it to a smaller size.

Possibly not trimming... What you might need to do is chopping the trunk well down below up to the first branch. Maybe use that branch as a new guide and start building from there. Right now, as it is, there is nothing much you can do but treat it as a house plant. In any case... Guidelines for this tree you can find it below:

www.bonsaiempire.com/tree-species/hawaiian-umbrella

P.S.: Compare your tree against the one that appears on this page and you´ll see what I meant.

Alain

I was kind of afraid you would say there's not much I can do with it.

Oh well, I've trimmed off branches and got roots going for new ones.