diff --git a/pkg/userns/userns_deprecated.go b/pkg/userns/userns_deprecated.go
deleted file mode 100644
index e1edbc44b..000000000
--- a/pkg/userns/userns_deprecated.go
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
-   Copyright The containerd Authors.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-// Deprecated: use github.com/moby/sys/user/userns
-package userns
-
-import "github.com/moby/sys/user/userns"
-
-// RunningInUserNS detects whether we are currently running in a Linux
-// user namespace and memoizes the result. It returns false on non-Linux
-// platforms.
-//
-// Deprecated: use [userns.RunningInUserNS].
-func RunningInUserNS() bool {
-	return userns.RunningInUserNS()
-}