Ok I'm sorry, yes you can most definitely prune an autoflower I do it all the time, some plants do not mind it at all while in others it may hold up your plant for a day it two, I do my first prune around day 30 to get my branches in the light, when it comes time to switch from food to bloom nutrients I then give a final prune exposing my branches and tops to my bloom light, use a pair of pruneing shears or fiskars, never use scissors on your plants, if you don't have shears or fiskars pinch off the leaves you want to prune, the first pic is a baby northern light, second pic a bit bigger but you can see where I pruned 2nd pic is just before my final prune before I switched to bloom nutrients, 3rd pic is after my final prune, and the 4th pic is 1 week in bloom, note the flower is starting to show structure after 1 week in bloom, note my tops and branches are exposed to the light, note where i pruned off some fans so my branches are in the light, your flower grows on branches so i prune to get them in the light, so yes you can absolutely prune an autoflower but you have to do it at the right time