What does the option Clear current data on Target store before migration mean?
“Clear current data on a Target store before Migration” additional option allows to delete the data on your Target store in compliance to the entities selected for an automated migration. For example: if you’re migrating “Products” and “Taxes” entities from Source to Target cart, this option will wipe out such entities on your Target store beforehand starting the transfer.
In case you’re performing multi-store migration, with option will delete the data from a store you’re moving to.
Note! This option is irreversible! It is highly recommended to make a backup before the migration.