I would like to trim off the part of my decal that is shown in the screenshot that I attached without needing to scratch it out nor attaching decals after decals.

Are you just needing to do some photo editing then? Like you are wanting to have the (what im guessing) tiretracks continue through without the extra smudges? I’m also guessing you are trying to make it into a tileable-texture? I think you might have a bit more luck posting texture\image\decal rel…