You’re in control of what you do on Togetherall. You can complete the activities at any time. If you do not wish to continue clicking through the chapters of the course you can simply leave. If you don’t like the course you don’t have to complete it.
However, to get the full benefit, it is always best to try to complete it if you can. Some of the skills you learn may not seem helpful now but may help you with issues that come up later. You can come back to a half-completed course at any time you wish and also once you have completed a course you can revisit any of the chapters again, if you wish.