If you have multi-type package repositories, you can use two scripts created to assist with kind of migration. There are multi-package repositories to single-type scripts, or depending on the way you choose to migrate, there are replication/export & import scripts. You will also need to move the irrelevant packages to a defined repository type from it. Follow this section on our Wiki to do so.
A. Before the replication or repositories export and import to from your on-prem Artifactory to your SaaS instance, run the PackageCheck.py script which will tell you which repositories are configured to support multiple package types, and what types those are.
B. Should you prefer to replicate or perform the export/import process you can use the PackageType.py - script to get a list of all your repositories, along with their package types and layouts.