diff --git a/dlls/mshtml/htmlwindow.c b/dlls/mshtml/htmlwindow.c
index d9ecf9d3d29..b6f66627dd9 100644
--- a/dlls/mshtml/htmlwindow.c
+++ b/dlls/mshtml/htmlwindow.c
@@ -3974,6 +3974,44 @@ HRESULT HTMLWindow_invoke(DispatchEx *dispex, DISPID id, LCID lcid, WORD flags,
     return hres;
 }
 
+static HRESULT HTMLWindow_delete(DispatchEx *dispex, DISPID id)
+{
+    HTMLInnerWindow *This = impl_from_DispatchEx(dispex);
+    DWORD idx = id - MSHTML_DISPID_CUSTOM_MIN;
+    global_prop_t *prop;
+    HRESULT hres = S_OK;
+
+    if(idx >= This->global_prop_cnt)
+        return DISP_E_MEMBERNOTFOUND;
+
+    prop = This->global_props + idx;
+    switch(prop->type) {
+    case GLOBAL_SCRIPTVAR: {
+        IDispatchEx *iface;
+        IDispatch *disp;
+
+        disp = get_script_disp(prop->script_host);
+        if(!disp)
+            return E_UNEXPECTED;
+
+        hres = IDispatch_QueryInterface(disp, &IID_IDispatchEx, (void**)&iface);
+        if(SUCCEEDED(hres)) {
+            hres = IDispatchEx_DeleteMemberByDispID(iface, prop->id);
+            IDispatchEx_Release(iface);
+        }else {
+            WARN("No IDispatchEx, so can't delete\n");
+            hres = S_OK;
+        }
+        IDispatch_Release(disp);
+        break;
+    }
+    default:
+        break;
+    }
+
+    return hres;
+}
+
 static HRESULT HTMLWindow_next_dispid(DispatchEx *dispex, DISPID id, DISPID *pid)
 {
     DWORD idx = (id == DISPID_STARTENUM) ? 0 : id - MSHTML_DISPID_CUSTOM_MIN + 1;
@@ -4200,6 +4238,7 @@ static const event_target_vtbl_t HTMLWindow_event_target_vtbl = {
         .lookup_dispid       = HTMLWindow_lookup_dispid,
         .find_dispid         = HTMLWindow_find_dispid,
         .invoke              = HTMLWindow_invoke,
+        .delete              = HTMLWindow_delete,
         .next_dispid         = HTMLWindow_next_dispid,
         .get_prop_desc       = HTMLWindow_get_prop_desc,
         .get_script_global   = HTMLWindow_get_script_global,
diff --git a/dlls/mshtml/tests/documentmode.js b/dlls/mshtml/tests/documentmode.js
index ca89fdadbdb..0ee20de7a90 100644
--- a/dlls/mshtml/tests/documentmode.js
+++ b/dlls/mshtml/tests/documentmode.js
@@ -1386,7 +1386,6 @@ sync_test("delete_prop", function() {
         r = (delete window.encodeURIComponent);
         ok(v >= 9, "did not get an expect exception deleting encodeURIComponent");
         ok(r, "delete returned " + r);
-        todo_wine.
         ok(!("encodeURIComponent" in obj), "encodeURIComponent is still in obj");
         window.encodeURIComponent = prop;
     }catch(ex) {
@@ -1424,7 +1423,6 @@ sync_test("delete_prop", function() {
         ok(r, "did not get an expected globalprop2 exception");
     }else {
         ok(!r, "got an unexpected exception");
-        todo_wine.
         ok(!("globalprop2" in obj), "globalprop2 is still in obj");
     }
 
@@ -1457,7 +1455,6 @@ sync_test("delete_prop", function() {
         r = (delete window.globalprop5);
         ok(v >= 9, "did not get an expected exception deleting globalprop5");
         ok(r, "delete returned " + r);
-        todo_wine.
         ok(!("globalprop5" in obj), "globalprop5 is still in obj");
     }catch(ex) {
         ok(v < 9, "expected exception deleting globalprop5");