Website down

Hi I think I made a mistake I enabled two system plug-ins for the Goggle recaptcha and joo captcha
since both of them are enabled my site stopped working.
Server error
The website encountered an error while retrieving It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this web page later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.

I ftp over to my site and uploaded a test html and it worked. So my question is how can I uninstall those two system plug ins without logging in to the joomla backend?
Any help is appreciated.

I 'm lucky i guess I manage to fix this problem!
In case people like to know how I did this for other user reference:
I went from the dream host web panel to phpMyAdmin and located the section
jos_plugins and deleted the 2 captcha related entry’s
now everything is working fine again
Thank You for trying to help