How can you relieve your cat in heat?

The only permanent solution is to have your cat spayed - once the ovaries are removed, she will no longer cycle and will not exhibit signs of heat.

Other temporary solutions would be allowing her to mate with a male cat - if you don't want kittens, you can try to find a vasectomized tom, seeing if you can find suitable alternative stimulation (some cats like a heating pad or a massaging pillow), or talking to your veterinarian about the possibility of hormonal control.