can't reduce polygon, non manifold edge

[yyumii]

Hi, 

I'm trying to lower the poly count in my scene but can not use the reduce tool because of non manifold edges. I have tried clean up but it does not have an effect, and I have tried to automate the UV but this does not help. 

Any suggestions?

Thanks

https://drive.google.com/file/d/1aMWCA8hCTew0pwiGe3QUUP9u-B_QiLfD/view?usp=sharing

[yyumii · Accepted solution]

Mesh>cleanup>

clean up matching polygons

apply to selected objects

keep construction history

non manifold edges

edges with zero length