Ability to Remove Donations (and Leave Space Empty) until Castle is Filled

There are times here and there that someone donates the wrong troop and you wish you could remove just that one or maybe a few troops and let someone else fill the request with the right troops.

I'd understand if it could not be done once the castle is filled, but it would be nice if up until it is filled, you have the option to drop the troops, to let someone else fill what it is you do need.

I'd also understand if the same person that filled it with the wrong troops wouldn't be allowed to just continue donating troops until the timer is up, and a request is made again, but i'm referring to letting someone who hasn't yet donated troops to let them fill what you actually need.

And even if to prevent people from using it to push the achievements there was a limit as to how many troops could be removed (i say troops not spaces, because some troops obviously occupy more space then others).

Even if we could just remove 5 troops from the castle and leave the space available for someone else to fill with the right troops it would be helpful.

One example would be, maybe i want my clan castle filled with archers, wizards, and minions for defense, and someone decides to or accidentally donates a few goblins. Rather than wait until timer is up so i can request again, it would be nice if i could remove the goblins and let someone else donate the troops i requested.

Thoughts?