diff --git a/imperative/python/megengine/autodiff/grad_manager.py b/imperative/python/megengine/autodiff/grad_manager.py
index 0cd44b38..db46b12e 100644
--- a/imperative/python/megengine/autodiff/grad_manager.py
+++ b/imperative/python/megengine/autodiff/grad_manager.py
@@ -100,21 +100,6 @@ class GradManager:
                 self._record_param(id(p))
         return self
 
-    def detach(self, params: list):
-        r"""
-        Remove specific registered parameters and callback functions.
-
-        :param params: registered parameters
-        """
-        if isinstance(params, Tensor):
-            params = [params]
-        for idx, param in enumerate(params):
-            if id(param) in self._param_dict:
-                self._param_dict.pop(id(param))
-                self._call_back_dict.pop(id(param))
-            else:
-                logger.warning("params with index {} is not attached.".format(idx))
-
     def _register_after_backward_callback(self, callback):
         self._after_backward_callback.append(callback)
         return self