Menu: Edit / Trim/Extend / Cut Corner

Cuts a portion off of the corner of a solid and replaces the corner with a flat face at a specified depth.

Point 1: Corner to be cut

In the Radius field, enter the depth – the distance from the corner along all of the edges that form the corner – to the flat surface.

Set a point on the corner. The corner is cut off to the specified depth, or radius.