The terrain delete does it work?

Everytime I try to make a pad for building I can use GM 1 and F7. I can create a box around the area but I cannot delete the terrain. Likely operator error but I need help

Quote from Groovaholic

Hi to remove the land you need to use F5 / 4 (area selection tool) then just drag the area that you need to remove once you are happy just hit the Delete key on your k/b job done.

OK was using the F7 function because it deleted trees and structures.. F5 then the 4 key (terrain selection) using the mouse or keys to select then Del key does erase it.. Thanks for the inspiration.

Sigh is really buggy works one time but not the next . Maybe it is a lag delay at the server. Seems if I hit the Del key once and wait it several seconds it works. If I get impatient and hit the DEL key twice it stops working.