Deleting content types

If a content type refuses to get deleted, saying that it's part of an installed feature, try checking the following:

• Deploy the solution that installs the feature.  And then activate and deactivate the feature.  (I am not clear on this part anymore; tried too many things.  And mumbling about SharePoint doesn't work.  I think the walk to the cookie store helped.)
• Delete all pages that use the content type
• Clean up the recycle bin of all pages that use the content type
• Go to the master and page layout gallery and delete all page layouts that use the content type

[Update 07-Oct-2011:]

Warning:  Some sections here may require deleting parts of a site collection.  I haven't found a better way.  Good thing I only needed to do it on a dev or test server.  DO NOT do on a production server; find a different way.

Use the tip from here (which I found on this StackOverflow thread) to query SQL to see what's still referencing the content type.  You may end up having to delete some subwebs. :-(

And then use the tip from one answer from the StackOverflow thread to 

• install the solution that had the feature that the offending content type
• activate and deactivate the feature
• go to the page layout gallery and delete the page layouts that came from the feature; make sure to clean them out of the recycle bin and from the site collection recycle bin
• I think, at this point, when everything related to the content type was cleaned out, it no longer appeared on the content type list.