I think it would be a good idea if Generals and Marshals could take down attack requests made by alliance members. Could this be a possibility in the future.
Why is this a good idea? If you place an attack request and your alliance mates decide to help out. If this is the case why don't you want attack request removed from the whole alliance and only Generals and Marshalls can make them.
The main problem is that any league member (full or probation) can make attack request on any other league member. And no one else can delete this request.