Hi there,
Do you know how to remove ink stains from leather with tartar, lemon juice, olive oil and vinegar? Well, I can tell you about it. For non-white leather, combine cream of tartar and lemon juice and make a paste. Then apply it on the affected spot and wait for a few hours. Then use a damp cloth and clean the surface. If you have white leather, use mix vinegar and olive oil. I read this information in an article that has many more cleaning options. I found the article beneficial for everyone thus sharing it here. If you want to know about the other cleaning options, read the article here.
https://www.bondcleaninginadelaide.com.au/how-to-remove-ink-stains-from-leather/