It looks to me that the "silver thing" is supposed to go all the way around the perimeter of the ram access area. Looks like it came loose, and it also looks like this iMac may have been taken apart previously & this loose "cushioning strip" is now out of place.
I'm guessing that the "silver thing" is a fabric like material...and is very flexible...so you could just flip it up out of the way of the ram release lever (push the lever all the way in, flip the fabric up, release the ram lever out).
I would say just cut/trim this loose fabric material...but without inspecting it personally (to make sure it is just fabric) I'm not going to say 100% you could cut it.
If you look at it carefully...this fabric material goes around the perimeter of the ram opening/access area...and so it probably serves as a cushioning/anti vibration material between the parts (no rattling). And like I mentioned above...it looks like this material became loose & is now out of place.
Thanks for the photo...that helps a lot!
- Nick