diff --git a/core/service.go b/core/service.go
index cdf25fc..9d284f3 100644
--- a/core/service.go
+++ b/core/service.go
@@ -883,6 +883,11 @@ func (sh *serviceDescription) delacc(w http.ResponseWriter, r *http.Request) {
 		delop = primitive.M{"$set": primitive.M{"_ts": primitive.NewDateTimeFromTime(curtime)}}
 
 		if originAuthType == AuthPlatformFirebaseAuth {
+			if sType == "guest" {
+				logger.Error("delacc failed. cannot delete a guest account.")
+				w.WriteHeader(http.StatusBadRequest)
+				return
+			}
 			sh.mongoClient.Delete(CollectionFirebaseUserInfo, bson.M{"firebaseuserid": sId})
 		}
 	} else {