This isn't really a question. It's also frequently requested as a feature in feedback about reconstruction mode. So they know we want it, but either don't want to give it to us, don't want to spend the time to develop it, or aren't satisfied with any attempted implementations yet (given that no changes are committed to city til after you save, how does a sold building get represented, do they allow you to unsell it - if it's simply unplaced things get deleted/sold as a batch, what if those unplaced things are valuable and someone clicks through a single confirmation window fast and loses half their city, is that extra inconvenience worth the extra convenience of being able to sell in the middle of a reconstruction)
For now... before reconstruction mode sell/store in advance at least a few things you know you want gone - and then squish the extras you decide during rearranging into the open space and sell them when you get out.