It is possible to change your parking stall.
There is a free option and a paid option. To pay a fee and switch your parking stall immediately, simply click on the stall you wish to switch it with on the iStall map, click "Register", and follow the prompts.
Switching for free is a little trickier. It will require you to cancel the renewal of your existing parking registration before the end of the current month as you are only allowed one reserved residential parking spot per month.
All monthly parking subscriptions are valid until the end of the month. Cancellations will end your subscription at the end of the month and stop future charges. It will also mark your stall as available to purchase to any other resident who doesn't have a parking registration (it will show up as yellow on the iStall map).
Note that you may not select a new stall until next month begins. It is therefore recommended to wait until close to midnight on the last day of the month to cancel your existing registration. At any time after midnight on the 1st, you can then select a new stall from what is available.
To cancel the renewal of your existing parking stall, check out the how to below.
Cancelling your renewal will not enable you to immediately select a new parking stall from available inventory without paying a fee. You will only be able to reserve a new parking stall for free after midnight on the beginning of the next month.