How to remove stain from leather patch on white jeans?

What you're talking about is "bleed" from the brown patch to the white of the jeans. That may be a tough one to get off, and you'd really have to be careful. I'd first spray the area that has the run off from brown with Shout and work it into the brown staining with a toothbrush. Try to get most of it out with the Shout. Then, if that doesn't get it, you'll have to try using a COLOR SAFE bleach to get the rest of it and work with the toothbrush. Do not wash these jeans in warm water. They, obviously shouldn't have been washed in warm water in the first place. BUT, if it says on the lable that warm was safe to use and that's what you did and this still happened, I'd try taking them back to the store!!! Good luck, but, if you work on it with the brush and the things I told you to use, it very well could come out.

Leaving leather wet like that to "air dry" is the real problem causer. You should have tumbled the jeans until almost dry than hung them up to finish if you wanted. You will have a tough time getting out the dye stain without aggressive stuff and possible damage to the fabric. It is true though that jean manufacturers have known about this problem for hundreds of years. They should only use completely dye-fast leather that can make it through a wash without bleeding. It is up to you to see if you want to risk trying to remove it or take it back and complain. It will still happen again if you leave the jeans wet for so long.

Just take some baking soda, mix it with a very small amount of vinegar to make a paste, and then put it on the carpet with an old toothbrush. Allow it to dry, then vacuum. If the stain is somewhat removed or lightened up, repeat again. Or small amount of Swarfega or WD-40. Worth testing a very small amount of these things to see what works best. Have also heard of the brown paper and iron method.

bleach it with a light bleech.