You must always cancel your stream before your Super Token balance reaches zero. It’s really easy to do from a few different places in the interface.
From the main dashboard, click the two down arrows next to the Super Token you want to see the streams of. Once you’re there, all streams have a cancel icon next to them in red. You can also cancel from any Super Token page, or on the Stream Details page.
Press cancel, and accept the transaction in your wallet.
After submitting, the transaction will show as processing for a moment.
Once the transaction is included in a block, the cancellation has been processed!