Doubled mesh - clean up ?

[silaeb]

Is there a way to clean up accidental faces that's are doubled up in the same mesh/ object . of course it renders bad , and that's my mistake .
I tried optimize .

 

[ZooHead]

Optimize will weld any polygons not already welded including doubles.

You may have to use a selection tool with visible checked.
Click once and only one of the polygons should be selected, then delete
and see if there's still one there. If it looks black you have to flip normals.

Before Optimizing you can try selecting one polygon and then use
Select Group to select any polygons connected to it, and see if you
can drag them away. If the whole thing moves they're all welded in already.

 

[silaeb]

Thank you so much !