Variation Wizard File Query

Im looking to remove some Child ASINS/SKUs from one of my Parent ASINS. This is where things get a little confusing... I downloaded the Variation Wizard file for said Parent ASIN and a lot of the data (including some REQUIRED data points) is missing.

For a bit of context, previously I had an agency working on my account who usually handled this kind of thing but I had to part ways with them.

But im just confused how so much of the REQUIRED data is missing from the Child ASINS? Because surely once I update my sheet and set the Child ASINS to Delete, it wont allow me to upload the sheet right? (because of the missing REQUIRED data) and how was my agency able to make such updates to my listings previously given the missing data?

Thankyou in advance!