Out of curiosity, I overclocked my pi to turbo. However, now when I start the pi, it freezes at the splash screen and refuses to boot. I am using the RetroPie OS. Is there anything that I can do in order to change the overclock setting so that I can boot the pi again? Would it be possible to read the SD card into my main computer and change the overclock settings?
Yes it would.
The various system configuration parameters, which would traditionally be edited and stored using a BIOS, are stored in an optional text file named config.txt. This is read by the GPU before the ARM CPU (and Linux) is initialised; therefore it must be located on the first (boot) partition of your SD card, alongside bootcode.bin and start.elf. This file is normally accessible as /boot/config.txt from Linux and must be edited as root; but from Windows or OS X it is seen as a file in the only accessible part of the card.