Deleting a layout is unrecoverable. No copy of it is stored on documents.logos.com, and Technical Support has no means to restore a deleted layout.
Please consider adding a delete confirmation (or undelete option from the documents website). Thank you!
Logos 8.0 SR-1 (8.0.0.0583) on macOS 10.14.1 (18B75)
See (L7) Restoring Layouts for the basis of this suggestion.