Thanks rocknrol for the helpful post!
Donyoung, when you click on the Fill Color drop-down box, you will see a list of all the available colors, then "none," then "Background." By selecting "Background" Solid Edge uses the color of your background sheet as the fill color for the text box.
I'm relatively new to Solid Edge, but am using V18. I have used created a Fill region, and have placed a text box on top of the Fill region. I then used the Text Box Properties, Border and Fill tab to a.) show a black outline, and b.) fill color white. This effectively blanked the Fill region...