George, you can either log in as root and remove it that way (do you know how to enable root user/log in as root?) or you can start up in OS 9, assuming you have a separate partition for 9, and delete it from there.
From the Help menu:
To enable the root user:
1. Open NetInfo Manager, located in Applications > Utilities.
2. Choose Security > Enable Root User and type a password for the root account. You may need to type an administrator password to make these changes.
3. Choose Apple menu > Log Out.
4. Choose Other in the Login window, type root in the Name field, and the root password in the Password field.
If you've already enabled root, then you simply need to log out and then log back in as root, using the password you've already established. Then, delete Mozilla and log out as root and back in as you usually do. That should work. Let us know.