Select the wall and then right mouse click.
CONNECT > Trim to roof/shell.
Select the shell to trim to and then select the portion of wall to keep.
Or you can use Solid Element Operation.
This is assuming you want to remove part of the wall above/below the shell.
Otherwise select both wall and shell then right mouse click.
CONNECT > Merge Elements.
This will keep both elements intact but will create the join.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11