implement deletion of admin user, frontend and backend

src/lib/server/userService.ts

@@ -32,5 +32,23 @@ export const addUser = (userName: string, userPassword: string): number => {
 	return rowCount;
 };
 
-export const deleteUser = () => {
+export const deleteUser = (userId: string) => {
+	// make sure to not delete the last entry
+	const deleteUserSQLStmt = `DELETE
+														 FROM users
+														 WHERE id = ?
+															 AND (SELECT COUNT(*) FROM users) > 1;`;
+
+	const statement = db.prepare(deleteUserSQLStmt);
+
+	let rowCount;
+	try {
+		const info = statement.run(userId);
+		rowCount = info.changes;
+	} catch (error) {
+		console.log(error);
+		rowCount = 0;
+	}
+
+	return rowCount;
 };