Files won't "Move" when I drag and drop, they only "Copy"
I'm trying to drag and drop files to an external drive off my Mac to free up space which, according to the Help menu, says it will move the files. However, dragging and dropping will only "Copy" the files. These files have read/write permissions, I checked. Are the directions incorrect? Is there no way to just "Move" the files? I have Mac OS Catalina.
MacBook Pro 13″, 10.15