The file could not be uploaded.When I try to upload image from article or basic page

Hi, I installed Starter theme Methys, I tried to upload a Slideshow image from local and I get the error: The file could not be uploaded.

I upload a new logo in theme settings and it was ok, only appers in Basic, articles editing pages.

Also apper in front:
Warning: unlink(/var/www/vhosts/jardindehara.com/httpdocs/2014/sites/default/files/field/slideshow/sl-3.jpg) [function.unlink]: Permission denied in drupal_unlink() (line 2202 of /var/www/vhosts/jardindehara.com/httpdocs/2014/includes/file.inc).

Could you help to me?
Thank you very much