By default, any object you create in BX is automatically visible. You can hide objects in your interface by selecting one or more and choosing the Hide option from the Resource Editor Component menu. You would commonly do this to Dialog boxes that would popup under control of the applications that you do not want visible at startup. "Hidden" objects will not appear until your application specifically "manages" them.

Note: Although the "Hide" option will have the side effect of cleaning up screen clutter, it performs a much different function. If you just want to cleanup screen clutter, see the question on "Can I set BX to only display the shells I am currently working on?".