The following guide will teach you how to completely remove the plugin from Redmine. You have to follow these steps:
Downgrade your database
Please navigate to the Redmine directory and execute the following command:bundle exec rake redmine:plugins NAME=redmineup_cms VERSION=0 RAILS_ENV=production
Delete the plugin's folder
To do so, please execute the following command as still being in the redmine/ directory:rm -fr plugins/redmineup_cms
Restart
Please restart your web server.
Video demonstration
Important: Currently, the plugin is renamed from "redmine_cms" to "redmineup_cms". In the below video old name is used. Please refer to the guide above in order to see the steps with the new name.