When adding a viewable to an active session in Creo View there is no way to then remove / delete that viewable without closing Creo View.
When production planning we may open a number of workpacks from Windchill to build a temporary visulation. We will sometimes append 5 or more viewables to a single session of Creo View as they are all assembled using a default CSY. These viewables can be quite large with many thousands or parts.
We do use Creo View MCAD which provides some powerfull capabilities although this simple function using Windchill cached viewables does not exist.