Fashion/ clothing help?

I’m not a seamstress by trade so I may be way off here but without any visuals to go by, I would say… Take out the outside seam and, depending on the fit, taper them down and in from either the hip or mid-thigh. I doubt you’ll get true a skinny jean look or fit but you may come close : )

Sounds ambitious! The seams on jeans are formidable…
I wonder if there will be issues with the fabric grain after modification? It could be different from normal for a skinny jean unless you take out both inside and outside seams and reduce fabric from both front and back parts.

If the jeans are made of traditional heavy denim like Levis 501s are I wouldn’t even try – that fabric is hard to sew without a special machine.

Before you cut anything put them on estimate how much fabric you would remove. Take the jeans off and pin along the inner and outer seams on the outside of the jeans (not the inside). Try them on and adjust the pins. Doing it with the outer side of the fabric out means you are pinning the right leg of the pants to fit your right leg, and the left to fit your left. This is important since your legs are not identical. Once you have it pinned where you want look at the jeans critically – are they hanging correctly? If so you can do the alteration. Don’t forget to leave extra fabric for the seam allowance when you cut.

Cheaper, easier and less frustrating to give the flair jeans to the thrift shop and purchase skinny ones.

Sewing two layers of denim requires a serious heavy-duty sewing machine.

Here is a reference on hemming jeans. And here is a reference on patching jeans. Both may give you ideas on how you might approach your conversion. As she mentions in the hemming tutorial, bulk is an issue. As the seamstress in the patching shows, maneuvering around the bulky seams is a challenge as well. If you do go ahead, there is something called a bump jumper (jean-a-ma-jig) for your sewing machine to help smoothly stitch over the thick seams.

So if you do want to go ahead and convert flares to skinny, put on the pants inside out, mark your knee-line and take in the seams on both sides of each pant-leg. Try to fold it such that you are stitching next to the original seam on both sides of the original seam, and do this on both seams on each leg. Use a long hand baste to test first before any permanent stitching and before any cutting. I picture this giving you four seams to stitch on each leg. Like she shows in the hemming tutorial. This will still leave you with the issue of bulk at the hem, and you may have to cut that off and redo the hem.

I took in the flare of a pair of twills and ended up with a pegged look because I didn’t balance the leg with reduction on both sides. Depending on the flare, the reduction of fabric may be uneven, say more on the outside of the leg and less on the inside of the leg.

Good Luck!

Jeans usually have some sort of “wash” on them that the hem and inside seem cannot be replicated once you cut away that material so I doubt you can make the jeans look really good, even if you get a matching thread for topsitching. It would depend somewhat on the particular pair of jeans.