I have a Nikon D90 and use a wireless remote, but there's a beep that I can't turn off?

When my camera is in remote mode and I press the shutter with the remote it makes a loud beep after every shot and I find it really annoying. It doesn't do it when I press the shutter release on the actual camera though. I can't find any setting to turn the sound off, is it even possible? Or do I just have to live with it

My guess is that the beep is to tell you that the cameras shutter actually activated. It would be a shame to take a lot of shots remotely to only later find that your remote was not aimed correctly and you ended up with NO photos.

The only other beep, the in-focus beep - can be shut off.

Look on page 180 of your user manual