Depends on how you want to log it. Some prefer different methods.
If you want to log it as PDPIC, then I suggest making a new column and making a new entry today. Put your total PIC mistake in parentheses to signal a subtraction, then add that time into your new PDPIC column. Put in the remarks section the reasoning and dates effected.
or..
You can do the strike-through method and adjust your totals beneath. Both are accepted as reasonable entries. Don't use whiteout it usually looks unprofessional, or you are trying to hide something.
Explain in future interviews that your instructor decided to log it this way. As a "Student pilot" you did not know better. But now that you have evolved into a "professional mature" pilot you have corrected the time accordingly.