Along the same wall you have two openings and on one you want casing and on the other you don’t. As a default the properties of the wall will put casing around both. Left click to select the opening that you want to remove the trim. Right click and select Properties. Under the Basic properties of the opening, uncheck Include Opening Trim. Now that one opening will not have trim around it. Hope that makes your Envisioneer work, one step easier!