Yes, by installing the wad, using any title deleter, or any number of other tools like mmm or wii mod lite
Careful, uninstall the wrong thing and you could brick
Edit: not much point in uninstalling when you can just overwrite. If u want the console to appear stock, then it wouldn't be enough to delete some cios's anyway, you would have to install stubbed ios's to that slot, which is again pointless