Change password on website

hi trying to find out how we can change password on our clubs website as the person who looked after it sadley passed away and we cant login to the site to update etc can anyone help us with this matter

There are instructions at the bottom of this page:

They explain how you can create an emergency user but it requires access to the system.

The solution to add a emergency user from the docs/quintagroup help page seems overly complex, why not run:

./bin/instance adduser username password

This adds an zope admin user, which can immediately be used. Also replace username / password with the credentials you want.

If know the username and the user has an e-mail stored and the password reset is properly configured (lots of ifs) you can just add a /login to your site's url and use the password reset feature.

Otherwise you need shell access to the server, go to the directory where Plone is installed in and proceed as @kcleong already explained.