diff --git a/webui/app.py b/webui/app.py
index 0c6cd5ef..08f1907a 100644
--- a/webui/app.py
+++ b/webui/app.py
@@ -1,6 +1,7 @@
 import json
 import os
 import sys
+import gc
 import tempfile
 from importlib.resources import files
 
@@ -178,6 +179,7 @@ def run_graphgen(params: WebuiParams, progress=gr.Progress()):
         "nodes": nodes,
     }
 
+    engine = None
     try:
         # 4. Initialize and Run Engine
         engine = Engine(config, operators)
@@ -214,6 +216,10 @@ def run_graphgen(params: WebuiParams, progress=gr.Progress()):
         raise gr.Error(f"Error occurred: {str(e)}")
 
     finally:
+        if engine:
+            del engine
+        gc.collect()
+
         # Clean up workspace
         cleanup_workspace(working_dir)  # Optional: keep for debugging or enable
 
diff --git a/webui/utils/cache.py b/webui/utils/cache.py
index 0c9412f2..eb537c49 100644
--- a/webui/utils/cache.py
+++ b/webui/utils/cache.py
@@ -1,5 +1,7 @@
 import os
 import shutil
+import stat
+import time
 import uuid
 
 
@@ -17,6 +19,14 @@ def setup_workspace(folder):
     return log_file, working_dir
 
 
-def cleanup_workspace(folder):
-    if os.path.exists(folder):
-        shutil.rmtree(folder)
+def cleanup_workspace(working_dir):
+    if not os.path.exists(working_dir):
+        return
+    st = os.stat(working_dir)
+    os.chmod(working_dir, st.st_mode | stat.S_IWRITE)
+
+    time.sleep(0.5)
+    try:
+        shutil.rmtree(working_dir)
+    except Exception:
+        pass