OS X is a great operating system but there are parts of it that can be deleted or trimmed without causing any problems.
This is because, by default, a standard OS X install contains some items that you personally will never need.
They're there because someone will use them, but you probably won't. The two main examples of this are the additional languages and printer files. Before you rush off to start deleting items from library folders, we must point out that you do so at your own risk.
If you're not sure what something is, it's best not to delete it. At the very least you ought to have a Time Machine or Carbon Copy Cloner-created backup of your system before you start deleting things, unless you are sure you know what you're doing.
Start from scratch
If you're installing or reinstalling a system from an OS X DVD, choose Custom Install and then deselect the additional printers and languages, and also the X11 and Developer Tools options. For the leanest system, deselect everything but the Base system.
If your Mac came preinstalled, have a look in Macintosh HD > Library > Printers and sort the list of folders by size to see if one is huge, filled with PPD files. The idea in including them is that OS X will be able to recognise many printers.
In truth, you only need the one driver for the printer you are running. You can delete these and reinstall the driver from manufacturer's website.
Getting rid of the languages on your system is a little trickier, as they don't just live in one place. There is a free program called Monolingual that is able to let you strip out all unwanted languages from your system. How often is an English speaker likely to need Arabic, Armenian or Afrikaans on their Mac? It is also able to remove unwanted architectures from your system.
In Universal applications, there is code to run the app on different CPUs. On an Intel Mac, for example, you won't need PowerPC G3 code. Getting rid of it can save space, but be warned, this is a dangerous thing to play around with.
If you accidentally erase architectures that you do need, at best you will break Rosetta, and at worst you will totally break your whole system. Similarly with the languages, if you accidentally remove English, you're in a lot of trouble.
In terms of applications you can safely delete more or less anything, since the apps themselves don't contribute to the running of the system, with a few minor exceptions like System Preferences.
You should leave the Utilities folder alone as well, since it contains assistants and the AirPort Utility to help you. Some programs come with uninstallers, which usually work by you running the installer and, rather than installing, choosing uninstall.
Unlike on Windows these tend to be pretty comprehensive and remove all components of an app, even the system and library files it may have buried on installation. For other programs, there's AppZapper. Billed as "The uninstaller Apple forgot", it lets you drag an app onto its window to delete all associated support files, caches and preferences as well as the app itself.
If you're a fan of installing programs to try them out, it's a great way to ensure that you safely remove them and their associated files when you have finished with them. There are similar programs around – AppDelete and AppCleaner being two of the best. AppCleaner is donationware so need not cost you anything. It also has a "protect" function to make specific apps immune from deletion.
As noted before, you can safely delete the GarageBand Apple Loops folder and iDVD themes from a standard OS X install if you don't need them. Deleting duplicate or unwanted tracks from iTunes is also a great space saver and clearing out obsolete photos from iPhoto will help with the clutter.
The Find function in OS X can be helpful here, as it lets you search using multiple criteria. So, for example, you could search for all items over 50MB in size that were last opened over one year ago, or something similar.
This would give you a list of items matching those criteria, which may well reveal large files or folders that you had forgotten about or lost. At that point you could decide to back them up or delete them altogether.
Slim the startup items
Startup items are another area where you can trim some fat. Some programs on installation place a startup item into your account so that a program or a helper starts up on login.
The worst culprits are printers and scanners, which tend to put clumsy and slow assistant programs in to load automatically, which slow down your login and without which the peripheral will almost always work perfectly. Go to System Preferences > Accounts > Login Items and delete any errant ones. You're unlikely to break anything by doing this.
Similarly, some installers add preference panes to System Preferences, generally to be found in the Other section. If these are no longer needed, right-click or [Ctrl]-click on them and choose Remove…, and they will be sent to the Trash. Similarly when you install widgets it can be easy to let them build up and forget the ones you never use.
To clear them out, open Widget Manager and you'll see a red symbol next to each one that can be deleted. Clicking this will send it to the Trash.
How to remove unwanted languages with Monolingual
1. Download and open Monolingual from the disc. Be very careful: if you're not confident with the process of stripping languages out of the system, stop now. If you are confident, then make sure the languages ticked are the ones you'll probably never use. Make sure that you don't click your native language.
2. Click Remove and the program will warn you that the step you're about to take cannot be undone without reinstalling the whole of OS X. Take this warning seriously. If you choose to continue, it will search the many localised files present on the system and inside applications and delete the ones you have specified.
3. The second tab is Input Menu, and here you can remove alternatives like Chinese and Korean; this won't reclaim a huge amount of space. Architectures can strip code from applications based on the code's CPU framework. This is best avoided; if you make a wrong move you could damage your system, necessitating a total reinstall.
First published in MacFormat, Issue 202