Plot3D without Shading, how to suppress it?

You need to:

• Set Glow on the surface. This adds a solid colour component to the shading.

• Set the other components to Black, to avoid reflecting any light.

This method does not require changing the global lighting, so it will not affect other objects in the scene.

Plot3D[
 Sin[x] Sin[y],
 {x, 0, 2 Pi}, {y, 0, 2 Pi},
 PlotStyle -> Directive[Black, Glow[Pink]]
 ]

In:

shading = Array[None &, {2, 2}]; (*{{None, None}, {None, None}}*)
Plot3D[Sin[x + y], {x, -Pi, Pi}, {y, -Pi, Pi}, MeshShading -> shading]

Out:

Another way is to set Ambient lighting on a white surface:

Plot3D[Sin[x] Sin[y], {x, 0, 2 Pi}, {y, 0, 2 Pi}, PlotStyle -> White, 
 Lighting -> {"Ambient", Pink}]

Or plot Pink and White light.