Creating a mass

[GegH1]

Someone will find this easy i'm sure. How do i create this as a mass?

Relatively new to Revit, teaching myself after 30 years on CAD

[syman2000]

First I would extrude the profile

Then extrude the wedge shape to cut off the rest

[GegH1]

Perfect

but when i delete the outside bits it reverts to the extruded form

What's the command to split them off