The message from the mod already settles the issue. Mods are encouraged to use their interpretation of the rules as much as possible and to improvise when there are no clear rules. That is what the mod did here by asking you to handle the posts yourself, rather than deleting them and you getting the automated notification.
Yup, the mod put it respectfully.
If you are asking if it is ethical to delete your own posts that have lost their context, it is to me.
Yes, but how can someone keep track of every post a person made quoting a spam/off-topic (deleted), also keeping in mind if there are multiple quoted posts and single one out of all gets deleted for being off-topic/spam. Then how will the person keep noticing this?, In Hot-Topics moderators can be responsible, but how can a handful mods will ask the poster(s) to delete multiple posts.
You are also not at any risk of plagiarism, you were not claiming the text.
- Jay -
Glad.