doesnt remove and invalid data url error

It might be because you've set a file directory path for the canvases. This doesnt work at all. See: http://drupal.org/node/1467714#comment-5848756

As a work around to the error you can either
1) Leave the file directory field blank
2) Go to admin/content and use the "update options" to delete from there

I fixed the error.

It's like i said, the file directory wasnt created.

So whatever file path you put you need to create it manually eg. if you put the file directory as "canvas" then you need to create a folder called canvas in your files folder.

Remember to change the permissions as well.