Managing problem sets is currently somewhat limited, you can view the criteria of a set and its results and delete unwanted problem sets. In the future editing functionality will be added, but for now you would have to create a new custom set.

The "Manage Problem Sets" button can be found on the left of the screen from the same "Problem Search" tab that you used to access the Advanced Search features.

After clicking on a problem set in the list of problem sets you then click either delete or show. By clicking show you will be given the search results based on the criteria of the problem set. If you wish to modify the set, you can change any of the options and chose the "Create Set" button to create a new custom problem set with the modified criteria (the original problem set will not be changed). If you click multiple problem sets, you can also click the Merge button, to merge multiple sets into one "super" set. Please see the Creating Merged Problem Sets section for more details on merging sets.