Disable Extension Requests for Your Class

You can turn off both automatic and manual extension requests for your class. You can grant extensions manually even if you turn off extension requests.

By default, when you create a new course, your students can request manual extensions, but not automatic extensions. When you copy a WebAssign section, the extension settings are copied over to the new course or section.

From the menu bar, click Communication.

If needed, select a class.
Expand Extensions and click Unanswered.
Click Settings in the top right corner of the message list.
Select Disable.
Click Apply.