Q: remove a app from my icloud account

What exactly does that mean? If you are trying to remove an app or anything from your purchase history, you can't. Purchases are always and will forever be tied to your Apple ID and they cannot be removed from the history.

You can hide the app if you like.

Hide and unhide purchases in the iTunes Store - Apple Support

Apps are not in your iCloud account. They are in your iTunes Store account. The two may have the same Apple ID, but they are still separate accounts. However, there is no way to remove them from the iTunes store account, as you bought them and you own them forever, whether you install them or not.