I hate to sound dumb

I have a new fx impact mark II And can’t find any where in the owners manual or on YouTube how to remove the .30 cal shroud, os I can remove the superior x liner and put in a pellet liner. With out removing the whole barrel assembly, on YouTube they show sliding shrouds and my .30 cal does not have a sliding shroud. And I just didn’t want to just start twisting on the shroud a damage something, I think once I get the shroud off I can remove the jam nut and change the liner. I thank every one for the last time I asked a question you all were a lot of help. 

Thank you sfc ret