How can you clean dark stains on a leather couch with home products?
This is a problem. First, try the simplest. Wipe with a damp - not wet- cloth. Then you should probably use saddle soap. This is a leather cleaning soap found wherever you can get shoe polish. I suspect that if your coach is light in color it will darken a bit. As David Fred has pointed out in the comments, saddle soap the whole coach if the area darkens.
If the saddle soap doesn’t work, you have a coach with a stain. Pretty cloth throws and pillows may help.