There are a few ways to remove shoe polish from shoes. 1) use a rubbing alcohol solution (i.e. 70% works, use 90% works the best but might strip the color so watch out), 2) use odorless mineral spirits (works really well, but again might strip color), 3) use a rag and brush to buff out as much as possible and wipe at them with a conditioner. There are also brand name "stripper" solutions like Tandy Leather, etc., but they are pretty caustic and shouldn't even be handled unless you have gloves.
Are these shoes finished with polish, dye, or a coating? If they are finished with polish or dye, you're going to have trouble getting the polish off without removing the dye. If they are finished with a coating over the authentic leather/skin, then you'll have no trouble stripping the polish without stripping the color. Most high end leather's are finished with coating that seals in the conditioners and allows you to polish over them. You can also buy these finishes and apply them yourself (i.e. SKUFF Protective Coatings), so you don't have to polish your shoes, or if you really insist on using polish, can remove it without problem.
If I were you, I'd recommend testing some 70% isopropyl alcohol on a spot to see if you remove any dye or just the polish. If you remove dye, then stop and try and buff it out. If you remove just the polish, then your shoes are finished and you can remove the rest. Either way, I recommend removing the polish and getting yourself an aftermarket shoe finish that shines your shoes and protects them from scuff marks. The best one I've found is SKUFF, because it does both and lasts for years. Plus, it comes with alcohol towelettes that you can use to clean the polish off before you apply it.
Just my two cents!