To uninstall a plugin, you can delete the folder: DATA_DIR/plugins/installed/name-of-a-plugin
Make sure the plugin is no longer used in DSS before deleting.
More about the DATA_DIR: https://doc.dataiku.com/dss/latest/operations/datadir.html
How do you achieve this for a Linux installation?
Entering command lines on the Linux server/computer hosting Dataiku DSS.
rm -rf /path/to/DATA_DIR/plugins/installed/name-of-a-plugin