We are experiencing a problem with deleted entities that had been created in a ‘dev’ project.
We need to recreate these same entities in the ‘production’ project, but this isn’t possible for the next 30 days 
We should have used dummy UUIDs rather than the ones that already existed.
Is there a way to empty the recycle bin so that we can recreate these entities in another project ?
The documentation and Kapa assistant mention a database workaround (at our own risks).
The goal with system ids is that they be entirely unique across the system. So we actually keep them after a purge also and don't allow their reuse.
That may not be practical for all contexts, especially when there are links between Entities. If you do need to reuse IDs, my recommendation would be to introduce a new custom column for that purpose. Your workflow would still need to use the system ids of Entities to update them but you could use your own ids for all other purposes.
For example, you could introduce a manual_id column and use the system IDs from your test Entities. Then you need to be very careful each time you do a query to use the correct ID. You could still use the system ID for all selects and lookups in the form and just save manual_id to the submissions or other Entities for linking purposes. Or you could add value=manual_id to your selects and change name queries in your form to use manual_id instead.
Let me know if you'd like a worked example for any of this.
Thanks Hélène, I understand we need to add a property to the entities that containd our own uuids and get it in the submissions with a calculate and a lookup.