This add-on used to work really well a few months ago but now it just keeps randomly removing the check boxes to delete scrobbles, as much as i liked this add-on in it's current state, it's unusable.
Dev, If you need any additional information feel free to let me know, i'll be happy to help.

The extension has a "can't read and change data on this site" error when you try to click on it. Completely grayed out.

Thank you for making this extension.
It was really hard to figure out how to use it. If it wasn't for a previous reviewer, I would've never known to look for delete in the address bar. After I selected the tracks, I didn't see a way to delete. I figured it out after clicking on the menu next to one of the tracks: I coudln't see it before because the option was not visible on my desktop browser.

Finally find one that actually works, thank you.

Works perfectly!
At first, I didn't see the icon for activating the checkboxes, but after mailing the developer, I got a quick reply explaining to me to look in the address bar. I should of course have seen it there, I can only blame my eyes. :)