Module Install crashes Drupal. How do I uninstall without deleting module from directory?

I installed a module last night with bad syntax. This caused the Drupal page to fail to load except that an error message was displayed about bad syntax. I need to work with the module developer to correct the issue but my question is this: is there a way to go into Drupal to tell it to deactivate the module? Every time I merely re-upload the files of the module now, Drupal "thinks" the module is installed because I enabled it once. How do I "un-enable" the module so that the mere adding of the files to the modules directory won't cause Drupal to crash.