Hi Everyone,
I would like to share with you guys, my step by step process of fixing this damage decal.
I received this GT Spirit Liberty Walk M4 (Blue Asian Version a few weeks ago). When I opened to see if there were any damages to this M4, I saw this.

Damaged Decal
The Liberty Walk decal somehow folded up during the clear coat process, and it got past QC. Which to me thinks it is a joke sometimes. I immediately contacted the reseller, in which they contacted GT on my behalf. And GT customer service quickly rectified the situation by air mailing (at their cost) the decals to fix up the problems.
I received the decals this week, and I finally had sometime to fix it up last night.

Replacement decals
So how to fix up this decal?
Once the decal has been placed, it is often sealed with a clear coat (I assume GT uses a urethane clear) it is really hard to remove them. You only have a few options (depending on the level of damaged to the decal)
1) Use 99% Isopropyl Alcohol. Using a q-tip you can slowly and gently rub the clear coat off the sealed damaged decal, and afterwards slowly chip away the decal with your finger nail. Be very careful of this process, as you may damage the paint below the decal. I've never personally use this method before, but I've used 99% Isopropyl Alcohol to strip paint of a resin model successfully. I've read somewhere online that this method works.
2) If the damage is not that bad, you can gently use a hobby knife to slowly chip away the decal. Again be very careful using this method.
In my situation, I used this method. After carefully examining damage decal, I noticed that I can use the tip of a sharp hobby knife to slowly and gently chip off the damage fold on the decal. I didn't want to completely remove the whole decal, just the damaged area.

Slowly removing damage decal.
Once the damaged pieces were removed, I just simply applied the new decal over the original decal.

Soaking decal in warm water.
Repaired done.

The decals that GT uses for their cars are very thin and fragile. I didn't want to over handle them. I did my best to align and place the new decal on top of the existing. I also didn't want to use MicroSet decal solvent on the new decal as I don't know how it will react to the MicroSet. And looking from afar, you would not have noticed that the original decal was damaged.
I'm pretty sure that there are many ways to fix this, but based on my past experience building models, I thought this was the best method.
BTW, I know Testors has a decal remover agent, but I've never used this product before. If anyone has any past experience fixing up or removing decals from a diecast model, please share.
Thank you
William
Happy Collecting!