Alt x

hello i have blender 279-b

in the image you can see what happens when i use ALT X
i do not know this function.
i have applied time ago an add on but i do not remember
can you help me?altx

Not sure, you must have this remapped to something since Alt X is used to delete unused nodes.

Open your preferences in 2.79b and goto input Select key-binding forn the field next to search and search for alt x It should show you the actual binding