How do I completely delete all the racks on a board file?
“Edit” -> “Global Deletions”
Make a backup before you do a “big” change and restore that backup.
Using ISO8601 dates is a very easy way to organize bacups.
Dropping files with names such as:
2018-06-10_Project.zip on an external device (NAS, USB stick) will automatically keep them organized.
I prefer to use Julian dates; but it does require a calculator or look-up sheet due to leap years.