Here's the thing.... It's physics. The higher the radio frequency, the smaller the antenna. So a 2.4ghz - or 2400mhz - radio has a small stubby antenna, and a 75mhz (or 27mhz) will have a longer antenna. The antenna length is tuned based on the transmitter. Changing the antenna length will affect performance and range.

You should never cut the antenna wire. If you find it to be too long, you can coil it and zip tie it and secure it inside the receiver box or chassis. You can then cut down the plastic tube to a more agreeable size. Test drive it, and see if your range or reception is affected. Generally radios of all frequencies in R/C have like a 1,000 ft range - which is pretty ridiculous. A couple hundred feet would be fine. So you can normally get by with coiling up the antenna and making it smaller.

Just make sure you're only cutting the plastic antenna tube. Those are like 99 cents at the hobby store and not a big deal if you need another. You don't want to cut the wire and have to send your receiver back to the factory to have it fixed.