To change the administrative password for your current Drupal installation you should:

1. Go to your cPanel -> Databases box -> phpMyAdmin;
2. Select the database which Drupal use from the drop-down menu on the left.
4. Click on the SQL tab.
5. In the text field on the page type the following text:

update users set pass=md5('NEWPASS') where uid = 1;

where "NEWPASS" is your new administrative password. Then click on the GO button and if no errors present, the Drupal password should have been changed.

If you are having problems resetting your Drupal password yourself, you may ask your host for assistance. SiteGround provides the best Drupal hosting and such requests are handled with ease.