Hi.
First you will need to change Moodle users auth method to "manual".
You will need to check Moodle users table, password file, to make sure it is filled. There has been some Joomdle versions where password were not synced to Moodle. If password is filled for all users, just changing auth method would be enough.
If you have users with a blank pasword field in moodle, you would need to copy password field from Joomla to Moodle database.
Finally, you can remove Joomdle in Joomla and Moodle, as described here:
www.joomdle.com/wiki/Removing
