What are the foods that are to be avoided if elevated serum creatinine?

Proteins. Persons with high creatinine have poor kidney function or even kidney failure. They must limit the amount of protein in the diet. Protein is the ultimate source of creatinine.
Not the key. The commonest cause for a person who feels well having a high creatinine is just being muscular -- when I was lifting weights every day, I ran 1.6 mg/dL or higher. A dose of ibuprofen can raise it. Food choices are not the key to managing most illness even when it is real. Older ideas about protein restriction apply only to clearly progressive kidney disease and are under review. Best wishes.