Saving space on your Mac hard drive is a key strategy, especially when you’re using a Macbook Air, with it’s strictly solid state drive (SSD). Even if you’re using a desktop Mac with a hard drive that seemed like “plenty of space” when you bought it, there will come a time when you’ll be looking to save some of it for more data. Why not get rid of the non-essential stuff on your Mac’s hard drive?
When you delete apps to help recover disk space, they can leave user cache files behind. These are the files that help improve the performance of OS X and various apps that are installed on your Mac. If you’re no longer using an app, you can delete these files to free up some space. Here’s how.
In the Finder, press Command-Shift-G or click on the Go menu, selecting Go To Folder. In the resulting field, type or paste ~/Library/Caches/. This will bring up the folder that contains the user caches. Once there, you’ll want to sort the list by size, which means you’ll want to set up that window to calculate all the sizes of files and folders.
Go to the View menu and choose Show View Options, or hit Command-J on your keyboard. Click the checkbox next to Calculate All Sizes and then close the View window. Your Mac will now show a number for everything in that Finder window, including folders. Now, if you don’t already, set the window to List view, either in the View menu or with a Command-2 on the keyboard.
You’ll now see all the biggest cache files near the top of the list (if you only see the smaller files at the top, click on Size again at the top of the column), and you can delete stuff that you no longer need. Spotify can have a bigger user cache file, as can some gaming apps.
Be careful not to remove anything you think you might need, of course. If you delete something that an app you still use needs, you might see some weird stuff go on with it.
Source: Cult of Mac.