To cancel your internal transfer / withdrawal request, simply click on your portfolio "transaction" tab (expand arrow)
Click on the withdrawal transaction
Click on the "Cancel Request" button on the bottom of your screen
Click on "Proceed" to submit the request to cancel your withdrawal request.
You are only able to cancel your internal transfer / withdrawal request if the status of the request is still in the "requested" state. Kindly note that once the internal transfer / withdrawal request started "processing", you will not be able to cancel it.