I want to take a DEM and edit it using a tool in ArcMap where it will take all the areas above a certain elevation and lower them all to the elevation I choose. For example, I would want everything above 2000 ft to be changed to 2000 ft so that it is flat at those areas. Any ideas on a good tool to do this?
You can use the "con" tool for reclassifying values in rasters. The conditional statement is the bread-and-butter of raster analysis and is a good thing to be familiar with.
The con tool can be found in the ArcToolbox: Spatial Analyst Tools > Conditional > Con
You can also do this via the raster calculator which, is my suggestion because you can define much more complicated conditional statements. Using raster algebra, a conditional statement takes the form of an IF/ELSE statement [IF elev >= 2000, THEN 2000, ELSE elev]
The raster calculator can be found in ArcToolbox: Spatial Analyst Tools > Map Algebra > Raster Calculator
The syntax for your question would be:
Con("dem" >= 2000, 2000, "dem")