Select your elevation group and then left mouse click where the extent of the deleted elevation is.
In the pet palette there is an option to "Revert Segment" (top right icon).
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