I have an umbrella plant/schefflera plant in my enclosure as well! I have an extra large reptibreeze cage. 24 x 24 x 48. And my plant isn't grown enough to reach the top but it goes out towards the sides and what I do is I get normal paper scissors and I curt the affecting branches and then I get a paper towel and a spray bottle with soapy water, spray the opening/ cut end of the stem and leaves and I then let it soak into the plant for 5 minutes then I get the paper towel and soak up the excess. My plant is then trimmed and safe. The sap is killed and it would not hurt your Cham. More less, umbrella plants are strong/hardy, cutting 1-3 branches that are not the main center stem, won't kill it. Hope this helped. Oh, by the way.. I'd recommend taking the Cham out during this process of removing the plant from enclosure. I just put my Cham on my shoulder while I do it.