Two ways, and you do not need to be leaving to use either.
At any time, yourself: every report can be downloaded from the portal with Generate, and tables can be exported to Excel. Nothing about your reports is locked in.
As a complete export: email support@sigill.tech and we will send your organisation's reports as a zip archive.
If you are terminating, ask for the export before the agreement ends. Terms for deletion are set out in the agreement and the privacy policy.