diff --git a/DINA-Web-API-Guidelines.md b/DINA-Web-API-Guidelines.md
index 0e50685..cdebae1 100755
--- a/DINA-Web-API-Guidelines.md
+++ b/DINA-Web-API-Guidelines.md
@@ -478,6 +478,13 @@ parameters, i.e.
  
 **[under-discussion]** Is this a MUST?
 
+### Delete
+
+In order to reduce inter-module reference issues while maintaining the system simplicity, resources **SHOULD** be deleted in a "soft-delete" manner.
+
+It implies that resources should not be completely deleted and still be resolvable after deletion. Such resources **SHOULD** return a `410 Gone` instead of a `404 Not Found`, with a body indicating how to access the deleted entity (e.g. sample/cf71a71e-2176-4d6f-9f17-a4c4f3dd104e?deleted=true). Deleted resources should not appear in a list operation.
+
+Hard-delete **MUST** be available for administrator to completely remove a resource if required (e.g. sensitive information).
 
 ### Supported languages