Saturated fat in the diet raises LDL cholesterol the most, so the main foods to cut back on are fatty cuts of meat, sausages and processed meats, butter, ghee, lard, full-fat cheese and cream, deep-fried foods, and baked goods like cakes, biscuits and pastries. Trans fats, found in some processed and fried foods, are especially harmful and best avoided.
Replacing these with unsaturated fats (olive and rapeseed oil, nuts, seeds, oily fish), more soluble fibre (oats, beans, lentils, fruit and vegetables) and wholegrains can lower cholesterol meaningfully.
Dietary cholesterol itself (for example in eggs) matters less for most people than saturated fat. A doctor or dietitian can tailor advice to your situation, especially if you have diabetes or have had a heart event, and can tell you whether diet alone is enough or whether medication is also needed.