When embedding an underground/subterranean architecture into the landscape, is there an easier way to dig all the terrain out from the building?

Hi guys, I’m an architecture student who is quite new to Unreal Engine. When I’m sculpting the landscape, I found it hard to get rid of all the terrain inside my underground building…Since it’s embedded into the landscape, what I’m doing right now is using sculpt tool to lower the landscape. But this method seems quite hard to achieve an accurate result and will harm the surrounding landscape surface. I wonder if there’s an easier way to take the landscape out?
Thanks guys