Whiteout looks bad and can be messy.
I once had an incorrect entry burried pages back which needed to be corrected from not only column totals, but page totals as well.
What I did here was make a new entry on the latest line which subtracted any errant entries. I may have also penned it in red, IIRC so it stands out. Essentially, youre just subtracting time which doesnt belong. This also works for adding missing time from a previously entered and calculated column, such as night.