Having seen the picture, your ginger plant has grown so tall because it's not getting enough light. The condition it's in is known as 'etiolated', which means it's lanky, with a thin weak stem and long gaps between leaves. Even if you reduce the height, it's unlikely to produce more normal growth unless you can improve light conditions.
UPDATE: Even a shady-ish spot outside will give more light to this plant than where it is now. Gingers don't exactly dislike the sun, but they definitely prefer partial shade, so dappled sunlight is fine, or a shady-ish spot. Being outside also means its subjected to breezes, which means the stem will thicken up over time. The one proviso is that it's warm enough outdoors, don't know where you are in the world, but if it is warm enough, you will need to harden this plant off before leaving out overnight. I'd chop it down by half at least, harden it off by leaving it outside during the day for increasing periods over 5 days, until it's out all night and can be left outside.