(Sorry… I don’t visit this page very often 
)…
Presuming you are indeed on Cubase Pro, then Score Settings>Layout. You’ll see, in the center section of the Layout window, the list of staves currently used, and, at the extreme left of the column headers, two “brackets”… one being the piano accolade, the other being a “straight” bracket. Just click on the one you want. (and if your current layout has multiple staves, you can drag the newly-appeared bracket, to encompass the desired number of staves.)