The fillets cannot be deleted anymore, there is no flat surface remaining between them. If you wish to move the filleted faces upper to meet the body shown later in the video, you can do two things:
- dirty way: cut away the fillet with a simple extrusion from a new sketch from a side view, you will have a flat surface again and it can be simply moved.
- cleaner way: select the filleted surfaces and instead of moving the arrows (which means you try to change the filler radius), select the Move/Rotate tool and move the face to meet the required height
If none of these give you the result you are looking for, I am happy to take a look at the .shapr workspace