Question: In Win7, an old version of Acrobat XI is still showing, but there is no matching MSI file for it to execute, so it can't "uninstall" and I can't delete the entry because MS makes it intentionally difficult.

Normally such things just pile up over time. But Acrobat *insists* on uninstalling the previous version and will not install until the old one is gone. 

How can I remove the entry from the database that "Programs and Features" uses?

![Programs and Features window](https://i.stack.imgur.com/HEH4h.png)

Answer: 
I had similar issues in the past and used [ccleaner](http://www.piriform.com/ccleaner) to clean up entires from "Programs and Features" after an uninstall went wrong. Hope it works for you.
This question is technically off topic as you are a user of the product not a developer of the product setup. Your cached MSI is missing and that's blocking their uninstall (bad design on their part) which occurs during upgrade to the new version. There are several things you can try:

1) Reinstall / Repair the old version and then try to uninstall it.

2) Contact the vendor for support.

3) Reinstall Windows.

4) Use the Windows Installer Cleanup Utility (no longer supported but can be found online ) to whack MSI's knowledge of the product. Note this doesn't actually uninstall the product and can cause all sorts of difficulties that may lead you to back to option 3.