Clean way to reduce polycount

Hay, i just added the free “Open World Demo Collection” pack to my scene. My problem is that all meshes do have a pretty high number of polys. Is there a good way the decrease the polycount to a more practical level so I can use them in my forest scene without losing to much detail?

PS: The only way i know is using Blender’s Decimate Modifier, but i haven’t heard many positive replies and i currently don’t have the cash to buy ZBrush.

See you

While searching, i came up with the hint that removing doubles actually works, but is there a way to bake a texture to a mesh within UE4?

Mesh Online has an affordable polygon reduction tool - ‘Mantis LOD Editor - Standalone Version 1.3.3’, it can import FBX files, reduce polygon count, then export to FBX files.