Look into mastodon.py - it doesn't provide exactly what you're asking for, but it exposes the tools you'd need to script a solution yourself.
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Next time please blur out the word windows on your posts. We have little children here and we dont want to encourage bad life choices. 
.py is the file extension for Python scripts, not the TLD of a URL. :)
Here’s the software and here’s the documentation.
youll have to install python at a minimum… might need a hand if you never worked with a python script. Be careful.
I wouldnt go that far… you could probably figure it out without too much difficulty. Would save you a lot of time too.
If you want i could probably do it quicker for you as a moderator then you can manually.
@DavidBond You may want to see if this one works for you: https://forget.codl.fr/about/
@DavidBond i know you can delete your account, which takes the posts with it. But I dont think you can delete just the posts. You'd have to delete your account then reclaim it then your posts would be wiped.