Can I stop taking Prilosec after 7 days? Today is the fourth day of treatment and I don't have any symptom.

What R U treating? If your goal of taking Prilosec was symptom relief, then the drug can be discontinued when no longer needed. However, if Prilosec was dispensed to therapeutically heal a damaged esophagus and stomach, then you are a long way from, but on your way to, cure based on symptom-response.