Resolve "addButton (for demo)"

services/database.ts

@@ -95,6 +95,17 @@ export const executeQuery = async (query: string) => {
     console.error("Query could not be executed!");
 };
 
+export const deleteExpenses = async () => {
+    try {
+        await db.transactionAsync(async (tx: SQLite.SQLTransactionAsync) => {
+            await tx.executeSqlAsync("DELETE FROM expense;");
+        }); 
+    } catch(error) {
+        console.log("Error deleting expense: ", error);
+        throw error;
+    }
+}
+
 export const deleteDatabase = () => {
     closeDatabase().then(() => {
         try {