If you need to stop a process from continuing onward, you can do so by halting that process.
To halt a process, first click on the process in your dashboard. Then click the button with three dots on it next to the "Go to next step" button at the bottom of the page. It looks like this:
You should see a popup with the option to "Halt this process". Just click on it and the process is halted. Halting a process is reversible. Deleting a process is not.
To Resume a halted process, simply click the three dots again on a process that has been halted, and you'll see the option to resume.
To delete a process (not reversible, so please don't use this option unless you're really sure) just click "Delete process".