Chrome does not offer a way of disabling an update for a specific extension.
If you want to make sure that you run some specific version of an extension, you could try any of the following options:
Read-only extension folder
Go to the directory containing the extension, and mark the directory as read-only. To find that directory, visit chrome://version
and look at the path at "Profile Path". The extension will then be at [value of Profile path]/Extensions/[32-character extension id]
.
Download the source code
Download the source code of the extension, and load it as an unpacked extension (or upload it to the Chrome Web store, and then install it).
There are several ways to get the source code (including just copying it from the directory as I mentioned at the previous step).
If you want to download a Chrome extension without installing it (e.g. because the new version contains unwanted "features" that you want to remove), then you could use my Chrome extension source viewer to download the code.
Some extensions expect to be run with a specific extension ID. You can forge this extension ID if you load the extension in unpacked mode (but you cannot upload the extension to the CWS if you do that). For instructions on fixing the extension ID, see How to change chrome packaged app id Or Why do we need key field in the manifest.json?.