If you need to decrease the size of your WordPress database, removing your post revisions is a great way to do it without sacrificing any actual content. To do this open the WordPress wp-config.php file and add the following configuration line to it above the “/* That’s all, stop editing! Happy blogging. */” line:
define('WP_POST_REVISIONS', false );
Doing this, however, will only tell your WordPress application to stop storing new post revisions. If you want to delete all the existing ones, it’s a good idea to use the Bulk Delete free plugin or a different one with similar functionalities.
If you do not want to disable the WordPress revisions functionality entirely, you can set a limit on how many revisions should be saved. This is done by adding the following line in the wp-config.php file above the “/* That’s all, stop editing! Happy blogging. */” line:
define('WP_POST_REVISIONS', 3 );
In the above, you can substitute 3 with the limit of revisions you want to have for each post.