1。 I think your view is the front view, so right-click the blank area of the front view and select "Unfreeze All" in the menu, which means to cancel all freezing.
2. Then use the red box to choose which pile of things you live in. Attention! Make him white (no choice? Choose with a box and frame him all! ! ! ! )
3. Just click "Delete" on the keyboard, which means delete.
Your problem will be solved.