My dedicated graphics card (Radeon 6470) seems to have broke and I want to use the on board Intel graphics instead, but I can't figure out how to switch to it. The bios on my laptop (HP pavilion dm4) doesn't let me do it and I don't know how it's done on the OS, I'm using Linux Mint.
In general, you cannot. In most computers, the BIOS will disable the embedded the graphics when an expansion GPU is installed. For most PC's, the only way to use the embedded graphics is to physically remove the card from the computer.