I want to try shell mesh but SW has hidden the control

I modeled a sheetmetal lipped channel by thin extruding the profile.

Having tried solid meshing, I now want to try shell meshing.

I cannot find a control for "shell mesh" even though Help points me to Mesh icon>Create mesh>Advanced>????

I tried converting the model to sheetmetal but  could not find an enabled control to do that.

What have I overlooked?

SolidworksSimulation