Adding Apple ID
As Bo A points out, in order to see more than just Repositories, you need to add an Apple ID.
Select Xcode -> Preferences...
On the Accounts tab, click on the + sign in the lower left corner and select Add Apple ID...
Fill out the required information and select Add.
This addresses the part of the question that indicates that the Accounts tab just shows Repositories.
Listing provisioning profiles
As Nikos M. points out, you can select an Apple ID and then the View Details... button to see your provisioning profiles (and signing identities).
Deleting provisioning profile
Another part of the question was asking about how to delete a provisioning profile (in addition to listing). It appears that there are two steps to this process:
Right click on a provisioning profile (that you listed from above) and select Show in Finder. You can then move the highlighted item to the trash.
Go to the Member Center on developer.apple.com and follow links to the section on Certificates, Identifiers & Profiles. Find and delete the provisioning profile of interest.
If you only remove the provisioning profile on developer.apple.com, I found that the profile still exists on your computer locally (not sure if it is eventually synced or if there is a way to force sync).
If you only remove the profile locally you may be okay for a while, but deleting and re-adding your Apple ID will cause the profile to reappear on your local machine.