Let's say I ordered a rifle like this and was under impression I can have them take off the bayonet @ discard at the gun shop (sadly), am I wrong and now screwed and have to send it back or can this be taken care of at the store?

I thought I heard you can do with bayonets and similar with ARs compliance but now I am not so sure, some people put doubt in my mind!

Even thought it is "permanent" you can just unscrew it correct?