Of course it is possible, BUT...... you will need to take the waistband off, probably re adjust all the spacing, of the pleats, unpicking and re sewing, beacuse if you are removing some of fell area, and the top of the aprons, you will also be increasing the waist size, and so on... the canvas might need to be moved the belt/buckle arrangements will need to be altered...... so I think it would almost be easier to start again....
It's not unusual for some kilts to have a hem at the bottom... still a lot of sewing, but it's likely to be less work..