Primary copy job will have dependency on sync copies with respect to Data Aging.
If you intend to break SDR and start with DASH, you first need to make sure the auxcopy doesn't have any jobs on it or non set as 'to-be-copied'. Make sure to delete these jobs from Auxcopy(SDR target) prior to breaking SDR, this way DB is clear and primary copy dependency is gracefully unlinked.
If you just take the target out, the DB will still know that these jobs existing on the Target copy and will be in an Orphan state. You can still go and delete them manually but that is goinga round in reverse.
If you intend to retain the jobs on target, the best way is to Migrate SDR to DASH. Thee way to achieve this is create another Deduplication auxcopy on the Storage Policy, and the the source copy for this auxcopy is the target auxcopy of the SDR replication. When you now run this new Auxcopym, it will seed all these jobs in to the Dedupe database on target MA and once done,you can change this new Auxcopy to copy from primary and then can get rid of SDR and old auxcopy.