You may change your limits the same way you set them in the first place. If you want to decrease your limits (making them more restrictive), the change will take place immediately.
If you want to remove or increase your limits (making them less restrictive), you will need to wait until the current limit expires. This means you must wait until the end of the day for a daily limit, the end of the week for a weekly limit, and the end of the month for a monthly limit. After entering the new limit, you will see the pending change until the time limit has passed.