To pause keywords from within Billy Grace, the first step is to head to the 'Keywords' or 'Keywords & Products' page. You can expand the table to keyword level, and you will see a 'Pause' button, as shown in the screenshot below:

Click on the button and press 'confirm'. After this, a job will start to pause your keyword. This should be finished within 20 minutes.

You can only pause active keywords, and currently Google is the only channel that is supported.