The roles, users and index based permissions will work, as these are part of the Community edition, the recommended approach would be to back up all of your configurations to a yaml file prior to making any changes with modules, just in case.
This is very easily done using the sgadmin.sh script with -r (–retrieve) argument, see example below:
./sgadmin.sh -icl -key "path/to/config/kirk-key.pem" -cert "path/to/config/kirk.pem" -cacert "path/to/config/root-ca.pem" -nhnv -r
If these are saved to sgconfig folder, they can then be loaded back to SG index using below command:
./sgadmin.sh -cd "path/to/plugins/search-guard-7/sgconfig" -icl -key "path/to/config/kirk-key.pem" -cert "path/to/config/kirk.pem" -cacert "path/to/config/root-ca.pem" -nhnv
To remove admin user, simple delete (or comment) the lines in the internal_users.yml file and re-upload using above command, please note if you made changes via UI or API, these will be overwritten, therefore backup is again advised.
In order to change the password, please use the hash.sh script provided to generate the necessary string and update the internal_users.yml file same way as mentioned above. Don’t forget to re-upload the configuration after.