I would like to replace the current custom skintone I have, but I'm not exactly sure which files of my long list of packages is the skintone, So when u install a new one, It won't overwrite the previous one

I was wondering if there is any possibility through sims3 start-program or something, to set one skintone as the default one?

As with all default replacement files, you need to remove one set before adding another to your game. Many creators will put "default" in the file name on a default replacement, but if you can't find it that way, you may simply have to re-download your current defaults to see what the file names are and remove 'em.

For the future, I strongly recommend organizing your downloads. If you have so many that you can't find these defaults via a quick scan of your file list, you should start foldering and subfoldering: Mods/Packages/Defaults/Skins.

Okay thx.. too bad they didn't keep the skintone settings from sims2, it was alot easier just picking one of your list of custom skintones