In the SMAX should be possible to delete records, at least for Tenant administrator:
Some of the records should not be deleted from SMAX (e.g. Offerings) due the process reasons (ITIL trasnfer into the Service Portfolio, when the Offerings is deactivated), but it could be possible to delete Offering, when Service catalog administrator makes mistak during Service catalog update.
Deleting of the record could create data inconsistency in case that the records is linked to other entites. Best way would be, if the SMAX would allow deletion only when the records has no associated records from other entities.