When forced to run a script in the Python window in ArcMap, or when it's easier to do so, change the environmental setting to prevent the intermediate layers from being added to the TOC.
######arcpy.env.addOutputsToMap = False
Change it back to True when you want the result to be added e.g
arcpy.env.workspace = r"C:\Some\Arb\Folder\work.gdb"
arcpy.env.addOutputsToMap = False
ftr_list = [arcpy.management.MakeFeatureLayer(ftr) for ftr in arcpy.ListFeatureClasses()]