There is a bug in Google Webmaster Tools right now where you cannot add, edit or delete URL parameters within the interface.

The issue started Thursday, January 24th and was reported in two different Google Webmaster Help threads.

When you access the interface to manage your URL parameters in Webmaster Tools, the buttons to edit or delete or even add parameters is simply not there.

Google’s John Mueller is aware of the issue and he said he has reported it to the appropriate team. John wrote:

There is no ETA for a fix.

Forum discussion at Google Webmaster Help.