Additional Information:
First, my webhost deactivated the Plugin “SEO Premium Plugin” by rename the folder. After, I could log into my backend, but I was not able to reach wp-admin/update-core.php to update my plugins / themes.
After, I decided to upload the latest version of Impreza. It totally crashed by website that i had to pull back my backups.
When the backup finished, I tried to rename the “SEO Premium Plugin” again to deactivate it. Now, it does not work. I cant even log into my Backend.