I have an image file open in ArcMap of an area of land and its land use categories. I would like to combine some of these categories together in order to simplify the map. For example, there is 4 "types" of developed lands listed and I would like to combine them to be just one single field called "Development".
Have you tried to reclassify? If you use the reclassify fields, you could input your lands layer, select the field you would like to edit (typically class name or ID), and assign new values. I've included a picture below from a previous project I've done. In this case I changed all of my fields besides Crops & pastures to be No data. But in your case, you could combine all of your development fields to be listed as "1".