You can manage your boosts from multiple locations, but the overall process to edit, manage, and delete your posts is the same. 

Navigate to the Content page, click Filters, and ensure "All Promotions" is selected for the "Paid Promotion" filter. Then click "View" adjacent to any piece of content, and within the Content History on the right side of the page you'll see any posts that have been boosted for that content. You can then click to view any individual post to view results and manage the boost.

Navigate to the Post Schedule page and use the Queued Content column and the Active Schedule column on the left and right hand sides of the page. Find the piece of content that you scheduled a boost for, have an active boost on, or want to boost. 

Navigate to an active boost and click on the hamburger icon to expand boost options, and then click "Pause Boost." 

To resume a boost, navigate to a paused boost, and then click the hamburger icon to select "Resume Boost." 

To add more money to a scheduled boost or change the boost duration, navigate to the active boost and click the hamburger icon to access the "Edit" option. Since the boost is active you can no longer change the audience.

To delete a boost, navigate to the boost in question, click the hamburger icon and select "Delete Boost".