Hi. Of course you can. To do this, open the Firefox settings menu and go to the "Privacy and Security" tab on the left. Find the "Passwords" menu and click the "Saved Passwords" button just below and to the right. This will open a tab displaying all your passwords. On the left, select the tab for the website for which you don't want to save your password and click it. On the right, click the "Delete" button. This will remove your data from this website, allowing you to manually enter your password each time you log in to that website.