Honestly I wouldnt even attempt the recolour. Most people here will give you advice on how to do it.

But in my opinion, you will never be able to get the right colour no matter much you try. I would suggest that you just keep the couch as is, or just get it re upholstered by professionals to any colour you'd like.

Get a leather cleaning kit. Most furniture shops sell them. It's really just a cream cleaner like sorbolene.

The main mistake people make is putting too much on & not wiping it off completely.

The leather is coated but still porous. If you don't wipe off properly, it sinks in & creates hard spots.

Just keep changing or using different parts of soft cloth to remove the dirt, or you'll just be re arranging it.

Never scrub just gentle circular motions & try it on the side arm or somewhere less noticeable first so you can see the results & you get the hang of it