Cocreate whiteboards may be found in older Gather Spaces (created before April 2021). On October 1, 2021, Gather discontinued support for Cocreate whiteboards.
If you have data stored on a Cocreate whiteboard that you don't want to lose, select SVG in Cocreate's toolbar to save your whiteboard's content. 
Select SVG at the bottom of the toolbar to save your whiteboard.
After our support ends, interacting with a Cocreate whiteboard will result in an error message. You can erase these whiteboard objects from your Space like any other object. Place a new whiteboard in your Space to create whiteboards powered by Eraser.