diff --git a/clientconn.go b/clientconn.go
index 0de8d464f85f..6b6e571b67b5 100644
--- a/clientconn.go
+++ b/clientconn.go
@@ -95,7 +95,7 @@ type dialOptions struct {
 	scChan      <-chan ServiceConfig
 	copts       transport.ConnectOptions
 	callOptions []CallOption
-	// This is to support v1 balancer.
+	// This is used by v1 balancer dial option WithBalancer to support v1 balancer.
 	balancerBuilder balancer.Builder
 	// The balancer to be used. Can not be overridden by service config.
 	balancerName string
@@ -210,15 +210,6 @@ func WithBalancer(b Balancer) DialOption {
 	}
 }
 
-// withBalancerBuilder is for testing only. Users using custom balancers should
-// register their balancer and use service config to choose the balancer to use.
-func withBalancerBuilder(b balancer.Builder) DialOption {
-	// TODO(bar) remove this when switching balancer is done.
-	return func(o *dialOptions) {
-		o.balancerBuilder = b
-	}
-}
-
 // WithBalancerName sets the balancer that the ClientConn will be initialized
 // with. Balancer registered with balancerName will be used. If no balancer was
 // registered by balancerName, pick_first will be used.