Yes. Here’s a quick ExifTool primer:
Output the current date tag values:
exiftool -AllDates /path/to/file.jpg
Set all date tag values to a different time:
Note that you need to provide “YYYY-MM-DD HH:MM:SS”). Note that ExifTool supports “0” for months and days, but I just found this out, so I need to change PhotoStructure to support unset months and days. Until then, just use the first of the month if you don’t know the day, or January if you don’t know the month.
exiftool -AllDates="2020-12-30 0:0:0" /path/to/file.jpg
Unset all date tag values:
If you’d rather just put images into yyyy-mm directories, use this command to delete the date tags from your files (-AllDates followed by an equal sign, then a space.)
exiftool -AllDates= /path/to/file.jpg