High Creatinine levels can be due to a few things

If you consume a lot of protein you can raise your levels

If you workout hard regularly it can raise your levels

or if your blood sugar levels have damaged your kidney's, it can raise your levels

To lower your levels, assuming its not a kidney problem, staying better hydrated and taking potassium supplements (BUT only IF you are not taking Blood Pressure Meds), reducing protein consumption and not working/working out so hard will help lower creatinine levels

But maybe get into your doctor and figure out "why" they are high

That will tell you how to lower them if it's possible in the first place..