How to remove paper texture from scanned image in Photoshop CC?

Posting a section of the image at original resolution would help.

I’m presuming that this is not a drum scan. Paper texture is often enhanced by the light/shadows cast in the direction of flatbed scanning… So the answer is often to scan a second time, rotating the image 180 degrees and combine so as to cancel out the original lighting direction, however it is almost impossible to scan and recombine the second image perfectly, which leads to softening of the image – which often leads to just as poor a result as filtering to remove the pattern. Scanning at a high optical resolution (not interpolated) and resampling down may also help, in combination with other efforts with judicious final sharpening of detail without sharpening of texture/grain or other nasties such as dust etc.

Sometimes one needs to filter the highlight areas with different settings than the midtones or shadows in order to clean up the texture. Probably also using an edge mask so as to retain edge sharpness while sacrificing some “flat surface” detail.

If you had a “copy rig” setup with appropriate lighting, then a good camera may provide an acceptable capture without the paper texture.

Depending on the paper texture being regular and not random – then FFT filtering using a third party plugin or tool may do a good job of removing or reducing the repeating texture pattern without degrading image quality too much.

Impossible to say without seeing how it looks. Usually that's what Image --> Calculations is for using tweaked duplicates of channels, possibly color space conversions on duplicate images and blending modes. Really depends how specific things are and how strongly the texture affects the colors.

Mylenium