simple. Just download widgetizer for removing all unnecessary things and wc3mapoptimizer for full protection. But first make a copy of the map u want to procect in case u want to edit it again.
Then just open widgetizer, select your map, check all boxes except ''custom key resistant'' and ''widgetize'' it. It will reduce the map size and improve loading. After widgetizing is complete, open wc3 map optimizer, select widgetized map and check every box and click save as(naame u want) and then ok. Your map will not be able to open anymore in WE, so no one could edit it.