The most easiest way is to edit the database either using mysql console client, or phpMyAdmin
on the users_users table give admin email fields your email address
then in tiki_preferences set forgotPass to 'y'
Now goto the tiki site, click the I forgot my password link, and type admin as the username
Check mailbox and Im sure you can guess the rest
- If you need the mysql username/password and database name, look in the db/local.php file.
- Blank the email address field out afterwards to save someone trying to gain control of admin afterwards. It will reset the password again, and could possibily be a security issue.