No matter you logout and login again, the error message still there and even did not allow you to go back to extension section to delete the extension which leads you error message.
1. If Yes, please go to opencart.com to dowload your opencart’s version and extract it.
2. Go to your shop by ftp, delete the folder “system” and replace it with new foler “system” which is just extract from your new download file.
3. Clear your computer’s cache memory.
4. Go back to your shop’s admin panel, log in and go to extensions section, delete the extension which leads you error message. done.