This routine does not seem to be used anywhere.

Index: sys/net/bridgectl.c
===================================================================
RCS file: /OpenBSD/src/sys/net/bridgectl.c,v
diff -u -p -u -p -r1.25 bridgectl.c
--- sys/net/bridgectl.c	25 Feb 2021 02:48:21 -0000	1.25
+++ sys/net/bridgectl.c	20 Sep 2026 16:47:44 -0000
@@ -840,14 +840,6 @@ bridge_tunneltag(struct mbuf *m)
 }
 
 void
-bridge_tunneluntag(struct mbuf *m)
-{
-	struct m_tag    *mtag;
-	if ((mtag = m_tag_find(m, PACKET_TAG_TUNNEL, NULL)) != NULL)
-		m_tag_delete(m, mtag);
-}
-
-void
 bridge_copyaddr(struct sockaddr *src, struct sockaddr *dst)
 {
 	if (src != NULL && src->sa_family != AF_UNSPEC)
Index: sys/net/if_bridge.h
===================================================================
RCS file: /OpenBSD/src/sys/net/if_bridge.h,v
diff -u -p -u -p -r1.77 if_bridge.h
--- sys/net/if_bridge.h	21 Nov 2025 04:44:26 -0000	1.77
+++ sys/net/if_bridge.h	20 Sep 2026 16:47:44 -0000
@@ -539,7 +539,6 @@ void	bridge_rtdelete(struct bridge_softc
 void	bridge_rtagenode(struct ifnet *, int);
 struct bridge_tunneltag *bridge_tunnel(struct mbuf *);
 struct bridge_tunneltag *bridge_tunneltag(struct mbuf *);
-void	bridge_tunneluntag(struct mbuf *);
 void	bridge_copyaddr(struct sockaddr *, struct sockaddr *);
 void	bridge_copytag(struct bridge_tunneltag *, struct bridge_tunneltag *);