Cut to 2D Clipboard (Ctrl+X)
Edit (Sketch/Sheet Level)

Use this command to cut (delete) entities and move
them to the 2D clipboard. Entities in the clipboard are overwritten when
new entities are cut or copied unless the save option is used.
First select the entities to cut. Then specify a reference point. This point will be used to paste the entities from the clipboard.
Clipboard - Use this option to save the current contents of the clipboard. Enter a name to save the clipboard as or pick the folder icon to select a previously saved clipboard using the Object Browser. The previous clipboard will be overwritten with the contents of the current clipboard.
When sketched Reference Geometry is cut to the clipboard its links to external geometry are broken and it becomes normal geometry.