When removing data from your Joomla website, you have to think about a couple of possible issues.
- When you remove an article, it will be moved to "trash". The article is still in the database, and can be restored. Only the state field in the database table has been changed.
To remove permanently, in Content > Articles > Search Tools (button) > set the "Select Status" filter to "Trashed", select the articles to be removed permanently and choose [Empty trash]
- Some extensions use "Versioning" meaning that when you save an existing item, the old item will be kept so that you can "roll back". If you remove information from an existing article when versioning is switched on, the removed information is still in the database and can be accessed via "Versions"
- When you remove a user, the user will be removed immediatelly and not be stored in "trash" like articles.
- When you remove a user that has written some articles, the articles will not have an associated user anymore, and administrators will retrieve see a warning.
Alternatively you can edit the user, remove or change their name + email address, and block it.
- Smart Search is a search method that completes your search keywords while typing them in the search box. In order to guess the words, it indexes all your articles. When you remove an article, the words might still be in the database tables of the smart search component (the database tables called "finder")
- Akeeba Backup might keep backups on the server
- RSForm Pro might store user input from forms in the database
Third party extensions for Joomla
- Create a "Forget me" functionality in Joomla. Registered users can wipe their profile with one click.
- Users can download a generated on the fly sheet with all their user related data.
- 3rd party extension developers can create plugins to extend this to their extensions as well
- More information: https://pixpro.net/labs/extensions/pixgdpr
RCP User (paid)
- Creates extra functionalty for the user manager
- It can automatically email and remove inactive users after a certain amount of time
- More information: https://extensions.joomla.org/extensions/extension/clients-a-communities/user-management/rcp-user/
RSForm Clean Up (free)
- CLI script to automatically remove RSForm form input after a certain time
- The script must be placed in the /cli/ folder of Joomla.
- In the script you can adjust how long the form input should be saved
- Using a crontab on the server, the script can be started automatically at specified times.
- More information: https://gist.github.com/pe7er/47bf1020b12ef29df8603fa80d1fdccd