Off the top of my head...depending on which version of InDesign you are using, you can delete the extension from the following locations:
- CS6 (8.0), CC (9.0), CC (9.1): C:\Users\<user>\AppData\Roaming\Adobe\CEPServiceManager4\extensions
- CC (9.2): C:\Users\<user>\AppData\Roaming\Adobe\CEP\extensions.(I think this is correct for 9.2, if not, it will be the same as 9.1).
- CC 2014 (10.0): C:\Users\<user>\AppData\Roaming\Adobe\CEP\extensions
Let me know if you need Mac paths.
Tim