Can still see deleted custom skins when I reopen Minecraft Launcher

I am trying to remove all custom skins from my Mojang account, but when I reopen the launcher I can still see or choose custom skins. It's so difficult to remove them completely, as when I try to reset or uninstall Minecraft Launcher, as it keeps happening. WHY DOES IT KEEP HAPPENING THAT I CAN'T MAKE ALL CUSTOM SKINS DISAPPEAR FROM THE SKIN LIBRARY?