To safely disconnect the battery from your car, you will need to follow these steps:

1. Locate the battery: The battery is typically located under the hood of your car, but its location may vary depending on the make and model of your vehicle.
2. Identify the positive and negative terminals: The positive terminal is usually marked with a “+” sign and is typically red in color, while the negative terminal is marked with a “-” sign and is typically black or dark in color.
3. Disconnect the negative cable first: Using a wrench, loosen and remove the cable connected to the negative terminal, making sure to keep the wrench away from any metal parts of the car to avoid short-circuits.
4. Disconnect the positive cable: Now, using the same wrench, loosen and remove the cable connected to the positive terminal.
5. Reconnecting the battery: Reattach the positive cable to the positive terminal first, and the negative cable to the negative terminal. Tighten the cables securely with the wrench.

It’s important to note that disconnecting the battery may cause the car computer to lose its memory and the radio will need to be reprogrammed. Some other electronic devices like alarm system, keyless entry, etc may be affected too.