Do you cut off the top of the sheets that you use for backing or just remove the thread and iron it out? I don't know what you would call it, a header maybe?

I have undone the seam before now, it depends if I needed the extra few inches.

I usually rip off the hems and sides. I know this seems wasteful but if they are torn they are squared-up. So many times I've found that the sheets are not squared or one side may be longer than the other.

I take em off to square them up,and then use the scraps in my string quilts.
Rae

I leave them on as I hate wasting fabric and sometimes really need those few extra inches. Any extra fabric is used to make matching pillowcases.

It all depends if I need the inches. If I need it, I'll unpick the hems. If I don't, off they come.

Try if using, to take if off by unraveling stitches, pressing them, then launder to see if the holes will go away.

Me too. Really makes it easier.

I unstitched once and used that part of a sheet to make pillow cases. The stitch line never went away; the holes are still there. So, now, I don't think I would use it unless I absolutely needed it,