Remove SKUs from a sales channel without deleting them

Unmap a sales channel from selected SKUs in bulk instead of deleting them, and re-run bulk edits for SKUs added later.

1. To stop SKUs appearing in a sales channel, do not delete them.

2. Bulk edits apply only to the SKUs selected at that moment, so SKUs added to the folder afterwards are not included and the same select-all plus Bulk Edit step must be repeated for them.