How To Shorten Armor?

[Blue Hatter]

Hello. I'm working on my first ever suit of trooper armor (which is a set of phase zero dark trooper armor) so I have a few questions about the process, but right now I primarily have one. The thigh armor is too long for me, I can't bend my legs when I put it around my thighs, and the leg armor could probably be shortened a little bit as well. How would I go about trying to shorten the armor while still keeping its look? The armor, of course, tapers in toward the bottom so I can't simply trim a bunch off the top or bottom or either the top will become too narrow or the bottom will become too wide... so I probably need to take something from the middle, leaving the two ends as they are... But how should I do that? How is shortening armor usually done?