In some raster images there are values that you do not want to display, especially backgrounds that contain information that does not represent the nature of the raster. In these homogeneous areas, they usually contain the value of zero in the case of Landsat images, and in digital elevation models -32767.
To remove the NoData values, this entry is intended to generate a surface that contains only the values corresponding to the raster variable. This first process is done through a reclassification. That is, the value to remove from the raster (0, or -32767) is identified and assigned to NoData. The rest of the categories are assigned the value of the unit. To do this open the Reclassify tool located in:
ArcToolbox > Spatial Analyst Tools > Reclass
Note that the value of -32767 (completely black in the image) is assigned NoData, all other categories (regardless of quantity) is assigned a value of 1. This process gives a mask of the study area. Now to generate a raster that stores only the values of the variable under study, in this case elevation. The initial raster (DEM) must be multiplied by the reclassified raster. To do this, use Raster Calculator located at:
ArcToolbox > Spatial Analyst Tools > Map Algebra
When the initial raster (DEM) is multiplied by the unit (Reclass_DEM), it only maintains the surface of the second. This removes the NoData values from a raster image.