You can update certain aspects of your release in the workstation. Things like the basic metadata (track titles, artists, P-Lines etc) and the assets (audio, artwork).
You can edit the release in the Workstation, in the catalog section by clicking through to your release.
These changes take approximately 14 days to take effect, and for any changes that are not listed here, like the start date or price tier you would need to contact the Support team through the Help box throughout the Workstation.