Fixed detach bug when disabling a new plugin

diff --git a/NinjaPanel.lua b/NinjaPanel.lua
index 75e83b0..5217353 100644
--- a/NinjaPanel.lua
+++ b/NinjaPanel.lua
@@ -364,7 +364,6 @@ function NinjaPanel:AttachPlugin(plugin, panelName)
 end

 function NinjaPanel:DetachPlugin(plugin)
-	plugin.panel.plugins[plugin.name] = nil
 	plugin.panel = nil
 	plugin.button:ClearAllPoints()
 	plugin.button:Hide()