WP-Optimize

It allows removing post revisions, comments in the spam queue or the un-approved ones.

Installation:

Unpack and upload it to the /wp-content/plugins/ directory.
Activate the plugin through the 'Plugins' menu in WordPress.

Features:

• Remove the WordPress post revisions
• Remove all the comments in the spam queue
• Remove all the un-approved comments
• Rename one username to another username, it's designed to rename default "Admin" user to something else
• Apply MySQL optimize commands on your database tables without phpMyAdmin.
• Display Database table statistics. Shows how much space can be optimized and how much space has been cleared.

What is new in this release:

• Removal of Akismet metadata from comments
• Removal of other stale metadata from comments
• InnoDB tables won't be optimized.
• Main screen user selection will be saved. Red items selection will not be saved
• Scheduled time display will be shown according to WordPress blog local time

What is new in version 1.8.6:

• Fix issues with total gain number problem.
• InnoDB tables detected and features disabled automatically, tables view will not show Overhead.

What is new in version 1.7.4:

• Added MYSQL and PHP versions beside the Optimizer tab.

What is new in version 1.7.2:

• All MySQL statements re-factored into native WP database calls - necessary for future versions of MySQL and WordPress.
• Upgrade to match WordPress 3.9 changes.
• Additional 2 languages.

What is new in version 1.6.2:

• Translation updates.

What is new in version 1.5.5:

• All the potentially dangerous clean up options are MARKED RED.
• Translations update for language - lv, de_DE, zh_TW, pt_BR, fa_IR, es_ES.

What is new in version 1.1.1:

• Fixed fatal error.

What is new in version 1.0.1:

• Removed auto cleanup of trackbacks or pingbacks. It's better for people to do it manually.

What is new in version 0.9.4:

• Non-initialized variables fixes.

What is new in version 0.9.2:

• Now the plugin is visible to site administrators only. Authors, Contributors, Editors won't be able to see it.

What is new in version 0.7.1:

• POST META Table cleanup code removed cause it is making problems with many hosts

Requirements:

• WordPress 3.7 or higher