Many folders have names that are the same as the app that created/uses the folder. If you know that you've deleted those apps you can delete the folder (either by using a file explorer app such as Astro on the phone, or by mounting the phone to your PC and using Windows Explorer).
If you happen to delete a folder for an app that's still on your phone, the app should re-create the folder next time it runs. However any data that was in the folder will be gone, so the app may not be just 'right' when you see it next.
Also, if you've backed up the folder to your computer, you have to option to bring it back if needed to fix a problem.