You will have to remove your barrel, no question about it. This is an easy job if you have a barrel wrench and a well anchored vise.
The gas tube just slips out after you remove the pin off the front sight post. Just pull it out of the post and into the receiver until it clears the post, then yank it out of the receiver. You might have to use a pair of plyers to coax and twist it out. After the tube is out, set the barrel on the vise and tighten really good (wrap the barrel in a sheat of leather to avoid scratches). Use the wrench to loosen the nut inside the delta ring; after removing the nut, the barrel will slide out.
The hard job will be to remove the front sight post. You need to put the post on a vise, upside down and with the barrel in a horizontal position. You'll need a correctly sized punch and a hammer to drive the pins out, which is no easy task. Most pins are tapered and only come out from one side, so make sure you push the smaller end. Some pins are straight, so it doesn't matter. After the pins are out, oil up the base at the barrel and carefully twist it out, trying to to scratch the finish too bad.
Of course, the delta ring assembly and barrel nut need to be removed also. They will just slide out after the front sight is removed.
To reassemble, reinstall the barrel on the receiver, slide in the nut of the floating handguard and tighten onto the receiver, making sure the holes align with the hole on the receiver. Now screw in the handguard. At this time install the gas tube on to the sight post. Slide the post back into the barrel, which is a tricky operation as the gas tube needs to line up perfectly with the hole in the handguard nut. Different people use different techniques to make the alignment easy, like sticking a shishkaboob stick into the receiver end of the tube, etc. After everything is is place, drive the pins back into the sight post holes.