[Groombug]

There're two retaining pins under the triangle sight - where the two posts hold around the barrel. Then there should be a hex nut you have to unscrew that's under the rear post, where the vertical sling mount would/should be. After that, take the handguards off, and you can unscrew the triangle assembly free from the handguard collar - if you so desire. If not, it should slide right off with the handguard collar still attached. Make sure you unscrew the flashhider first, too.