I need to reduce my polygon count from 400,000 to below 100,000 to export as OBJ (to fix other problems)

When I reduce the number of triangles or reduce by percentage, it completely shatters the geometry with the error message:

// Error: line 0: Current selection doesn't match required selection type. //

I've cleaned up non-manifold geometry and fixed holes. Next step is to pull my own eyes out.

Any help appreciated

@immakid

first u click reduce - done
then u go into its attrs - (reduce options?)
then u see where it says sharpness
then u change sharpness to 0 - reduce options > shape > sharpness=0 done
then u press 3 - just press the 3 button? What field?
then its smooth and good