Where did I say that? We pray to God, Our Lady, the angels and saints to "deliver" us and bring us relief. But we do not command demons whom we imagine to be the cause of such things.
If we are only imagining that demons are causing problems, then there won't be any effect whatsoever, of course, since the problem is only in our imagination. You seem to assume that it can only be an imaginary thing, and not real. And if that's the case, where is the problem?