diff --git a/src/Input/Parser.php b/src/Input/Parser.php
index ba1c81a..f710d68 100644
--- a/src/Input/Parser.php
+++ b/src/Input/Parser.php
@@ -248,6 +248,18 @@ protected function register(Parameter $param)
         $this->set($name, $param->default());
     }
 
+    /**
+     * unset a registered argument/option.
+     *
+     * @param string $name
+     */
+    public function unset($name)
+    {
+        unset($this->_values[$name], $this->_arguments[$name], $this->_options[$name]);
+
+        return $this;
+    }
+
     /**
      * What if the given name is already registered.
      *
diff --git a/tests/Input/CommandTest.php b/tests/Input/CommandTest.php
index f385641..4f3059b 100644
--- a/tests/Input/CommandTest.php
+++ b/tests/Input/CommandTest.php
@@ -261,6 +261,16 @@ public function test_bind()
         $this->assertNull($c->app());
     }
 
+    public function test_unset()
+    {
+        $c = $this->newCommand();
+        $this->assertCount(3, $c->allOptions());
+        $this->assertArrayHasKey('verbosity', $c->allOptions());
+        $c->unset('verbosity');
+        $this->assertCount(2, $c->allOptions());
+        $this->assertArrayNotHasKey('verbosity', $c->allOptions());
+    }
+
     protected function newCommand(string $version = '0.0.1', string $desc = '', bool $allowUnknown = false, $app = null)
     {
         $p = new Command('cmd', $desc, $allowUnknown, $app);