How to find all GameObjects in a parent in shorter code than I figured out

Questions & Answers
1

I’m trying to find a way but it seems many Question for GameObject and answer to that points me to Transform

I want GameObject not transform

and my ending doing codes:

foreach( GameObject GOs in gameObject) {
    Destroy(GOs);
}

Assets/Scripts/CreateFloor.cs(164,17): error CS1579: foreach statement cannot operate on variables of type `UnityEngine.GameObject' because it does not contain a definition for `GetEnumerator' or is not accessible

foreach( GameObject GOs in transform) {
    Destroy(GOs);
}

seems to work fine but when I test it

InvalidCastException: Cannot cast from source type to destination type.
CreateFloor.DestroyFloorF () (at Assets/Scripts/CreateFloor.cs:164)
ShowFloor.OnTriggerExit (UnityEngine.Collider Other) (at Assets/Scripts/ShowFloor.cs:47)

and at last this one seems to be working:

List<GameObject> children = new List<GameObject>();
foreach (Transform child in transform) children.Add(child.gameObject);
for (int i = 0; i < children.Count; i++) {
	Destroy(children*);*

}
witch seems to me a bit big and clumsy is this the only way to get rid of children? and I want to destroy them. not deactivate or anything.
[1]: Recursively get all children - Questions & Answers - Unity Discussions
[2]: How To Get List of Child Game Objects - Questions & Answers - Unity Discussions
[3]: How to get an array of all children of any type, but not their children ? - Questions & Answers - Unity Discussions

2

I think you just want to do this:

foreach (Transform child in transform) {
    Destroy(child.gameObject);
}