How to resample DEM

I am thinking about resampling tiff data. I would like to scaledown the image from 2 m to 30 m eventually.

I would like to make the 15*15 grid and then I would like to make them 1 grid. I could do that by using blkrock (or blokproc), but I could not reflect the x y coordinate. They still remain 2 m resolution. Does anybody have any idea?