From your Chessable dashboard, click on the course to go to its chapter list:
Click on the right chapter.
Scroll down and you should find the chapter options just below the course options.
You will find three options:
Pause all variations: Pausing all of the variations in the chapter will remove them from your review queue and the default learning sequence.
Delete my progress: Removes all of your progress within the chapter. Chessable will treat all of the chapter's variations (trainable or otherwise) as if you're seeing them for the first time. Note that deleting your progress cannot be undone.
Fast-forward time (FFT): Selecting this option schedules all of the chapter's learned moves/variations for immediate review. You need a token to use FFT, available from the ruby store.