Revisions function ¿disabled?

It’s not a good idea to run old versions of WordPress. Fortunately, you can quite easily turn off post revisions by using the wp_revisions_to_keep filter.

Add the following code snippet to a plugin, or to your active theme’s functions.php file:

add_filter( 'wp_revisions_to_keep', 'wpse_368635_disable_revisions' );
function wpse_368635_disable_revisions( $revisions ) {
    // Setting the value to 0 will disable revisions.
    return 0;
}

This will disable post revisions, except for a single autosave. See Revisions for more information.