The iMac, when running Mac OS X, stores deleted files in a trash folder. The trash folder has a shortcut on the Dock, but it can be difficult to find by exploring the file system.
Mac OS X is built on top of the Unix operating system, and one of the traits of that OS is that it hides folders by giving them a name beginning with a period (.). One such folder is the trash folder, which is located in every user's home directory in the ".trash" folder.
Access from Terminal
The simplest way to access this folder, if the trash icon is missing from the Dock, is by opening the Terminal, which is located in the /Applications/Utilities folder. Once you've opened the Terminal, type the following:
"cd" is the Unix command for "change directory" and the tilde (~) is a shortcut for the current user's home directory.
External hard drives or flash drives may have hidden ".Trashes" folders on them as well to hold any data deleted from them.