diff --git a/napalm_proxmox/vm_provision_mixin.py b/napalm_proxmox/vm_provision_mixin.py
index 3bd2344..7c9935e 100644
--- a/napalm_proxmox/vm_provision_mixin.py
+++ b/napalm_proxmox/vm_provision_mixin.py
@@ -476,11 +476,16 @@ class ProxmoxVMProvisionMixin:
                 _logger.debug(f"VM {vmid} stop failed (may already be stopped): {e}")
 
             # Step 2: Delete VM
+            # Proxmox's API parameter is hyphenated (destroy-unreferenced-disks),
+            # not a valid Python identifier — proxmoxer forwards kwargs to the
+            # request verbatim with no underscore-to-hyphen translation, so this
+            # must be built as a dict and unpacked rather than passed as a kwarg.
             _logger.debug(f"Deleting VM {vmid} configuration and disks")
-            self._node_api().qemu(vmid_int).delete(
-                purge=1,
-                destroy_unreferenced_disks=1 if remove_disk else 0,
-            )
+            delete_params = {
+                "purge": 1,
+                "destroy-unreferenced-disks": 1 if remove_disk else 0,
+            }
+            self._node_api().qemu(vmid_int).delete(**delete_params)
 
             # Step 3: Clean up Cloud-Init snippets
             # (This is best-effort; snippet files may be unreachable if storage is unavailable)
diff --git a/tests/test_vm_provision_mixin.py b/tests/test_vm_provision_mixin.py
index 12e9b07..14eb99f 100644
--- a/tests/test_vm_provision_mixin.py
+++ b/tests/test_vm_provision_mixin.py
@@ -451,6 +451,11 @@ def test_destroy_vm_success():
         mixin.destroy_vm("101", remove_disk=True, timeout=60)
 
     assert mock_vm.delete.called
+    # Proxmox's API parameter is hyphenated; passing the underscore form
+    # (a Python-identifier-friendly typo) gets silently rejected by Proxmox
+    # with a 400 "property is not defined in schema" instead of deleting.
+    _, delete_kwargs = mock_vm.delete.call_args
+    assert delete_kwargs == {"purge": 1, "destroy-unreferenced-disks": 1}
 
 
 def test_destroy_vm_already_stopped():