Here are the Steps on how you can Change your Wordpress site password in phpMyAdmin:
Step 1: Login to your site's cPanel. To do this put “/cpanel” at the end of your site's link address.
ex. ( www.yoursiteaddress.com/cpanel )
Step 2: Look for phpMyAdmin logo and click it.
Wordpress database (if you installed this through QuickInstall, this will be named wrdp#) from the left hand side.
Step 4: Look for wp_users on the list of tables and then click it.
Step 7: Lastly, Click Go at the bottom to save changes.