A simple way to remove all the old revisions of WordPress posts..
The Plugin named “Optimize Database after Deleting Revisions” is excellent for removing all the old revisions of both posts and pages that are taking up space in a database, and maybe slowing down a website.
Link: https://wordpress.org/plugins/rvg-optimize-database/
Main Features
Deletes redundant revisions of posts and pages (you optionally can keep an ‘x’-amount of the most recent revisions)
Deletes trashed posts, pages and comments (optional)
Deletes spammed comments (optional)
Deletes unused tags (optional)
Deletes ‘expired transients’ (optional)
Deletes ‘pingbacks’ and ‘trackbacks’ (optional)
Deletes ‘orphan postmeta items’
Optimizes the database tables (optionally you can exclude certain tables from optimization)
Creates a log file of the optimizations (optional)
Optimization can be scheduled to automatically run once hourly, twice daily, once daily or once weekly at a specific time (optional)
‘Optimize DB (1 click)’ link in the admin bar (optional)
‘Optimize Database’ Icon in the admin menu (optional)
An example of the savings on a small and new website:
WordPress Plugin Tips
60.1 - 873,784
This works well, and trimmed out many revisions, I set it to leave just 1 revision. It trimmed 41.5 MB on the first run, reducing the database size down to 68.12 MB from 109 MB
But the fact that it can also automatically remove all comments marked as spam saves me another job each day. 5 stars for this.