The process to shorten the draw length would depend on what the bow is capable of and what your specific draw length is. So, what draw length are you trying to get?
If the bow is a SHORT. Aeroforce X-80 is can be adjusted from 26" to 28"(24" and 25" is also possible with optional modules). If the bow is a MED. Aeroforce X-80 is can be adjusted from 29" to 31". A LONG Aeroforce would be adjustable from 32" to 34" of draw length. Keep in mind that within these draw length ranges, the specific draw length and let-off percentage are adjusted by changing the module on the cams. It's really not very complicated other than that.