Hi :)
I would say that the building still contains a swimming pool, even though it's not used anymore. Instead of deleting the node for the pool, I would therefore suggest to add `disused:leisure=swimming_pool` to it instead. In theory, it could be re-activated pretty quickly. If the building is teared down in the future, or the swimming pool removed entirely, the node can be dropped.
Would you agree with that?
Kind regards, Crsi

I have resolved the change in osm.org/changeset/130045503

The node osm.org/node/1567316540 already describes McDonalds here. Are you sure that the musical instrument shop 'Peter Erben' doesn't exist anymore at this place? If that's the case, then remove this node in favor of the existing McDonalds node above. Otherwise, please revert this change, and possibly correct it accordingly (e.g. by adding opening hours). I would be glad to help if further assistance is needed.