To cancel your membership, go to My Account → Wallet → Rebag+ → Manage Membership, and select Cancel. You will lose all of your benefits the day of your cancellation. Your R+ Credit, including the bonus already awarded, can still be used on future purchases.
Before canceling, consider opting to skip a month instead. Skipping only pauses your membership benefits for one month. If you skip, you miss one monthly 2% bonus, while if you cancel, all benefits are forfeited on the day of cancellation and all contributions made before the canceling will lose any potential future 2% monthly bonus.