I noticed that my delta ring needs to be replaced and was wondering if it can be pulled off from the receiver end by removing snap-ring and weld spring? Does index pin have to be removed?
Thanks

It is removed from the barrel nut assembly, after you remove the barrel nut. Is the damage cosmetic, or functional damage?  

Edited- realized after initial reply that it could be removed after barrel nut is removed from upper, then barrel slid out from upper, then removed from barrel nut and right over the rear of the barrel. All my barrels have 2 piece float tubes.

The delta ring will not clear the barrel nut.  It is always removed off the chamber end of the barrel.  You will have to remove the barrel to replace the delta ring.  Pull the snap ring and spring.  Index pin can stay put.

The gas tube and barrel has to come off the receiver then the "C" clip taken off the nut.  The wave washer and delta ring slide off the nut.  The nut stays on the barrel.

Hoppy

SBR7_11
I always heard that the only way to replace the delta was off the front... then I started looking at it and thought "what's that snap ring doing besides holding on the weld spring and delta ring.

It is cosmetic damage (small crack) but will probably be a functional problem before too long.

Looks like some other members have seen (done) what I discovered... remove the snap-ring, weld spring and it should slide off the chamber end!

Amazing what can be figured out with a little thought. This was the last remaining AR15 part that I had no experience in removing or installing. I feel so complete!
Thanks to all for the help.