The best way to create a boundary is to use Smoothed_DEM layer as the extent of the campus area. To be able to create a polygon out of a raster, you will need a raster with integer values. The current raster values are float. On the ribbon, on the Analysis tab, click Tools under Geoprocessing and search Int. Click Int (Spatial Analysis). The input layer is Smoothed_DEM and rename the output raster to DEM_int. Click Run.
Select Raster Calculator (Spatial Analyst Tools). Using Raster calculator, multiply DEM_int by 0 to create a constant value raster.
Name the output raster as rasterzero. Click run. Now you have a raster with value of 0.
Go back to Geoprocessing Tools tab. Search or raster to polygon tool. Click Raster to Polygon (Conversion Tools). Convert rasterzero layer. Save the output polygon as Boundary. Click Run.
Remove rasterzero from Contents pane. You don’t need it anymore. Change the symbology of the Boundary layer to no fill, color with Tuscan Red, outline with the width of 2pt.
Turn off FLD_HAZ_FEMA. And make sure that FLD_HAZ_Campus is located under UP_Buildiing. This will be the result.