In Google Chrome, you will want to not only turn off autofill data, but also clear it.

Turning Off Autofill in Chrome
1. Click the Chrome menu icon. (Three dots at top right of screen.)
2. Click on Settings.
3. In the “Autofill” section, expand the area for which you wish to disable Autofill.
4. Toggle the setting OFF if it is on. The system will automatically save your settings.

Clearing Autofill Data in Chrome
1. Click the Chrome menu icon. (Three dots at top right of screen.)
2. Click on History, then click on History again in the menu that appears.
3. Select Clear browsing data. (Alternatively, you can press CTRL+SHIFT+DEL on your keyboard to bypass steps 1-3.)
4. At the top, choose “the beginning of time” option to clear all saved data.
5. Make sure that the “Clear saved Autofill form data” option is checked.
6. Click Clear browsing data.

Similarly, in Firefox, you will want to not only turn off autofill data, but also clear it.

Turning off Autofill in Firefox
1. Click on the Firefox menu icon. (Three lines at top right of screen.)
2. Click on Options.
3. Choose “Privacy & Security.”
4. In the “Forms & Autofill” section uncheck “Autofill Addresses.” The system will automatically save your settings.

Clearing Autofill Data in Firefox
1. Click on the Firefox menu icon. (Three lines at top right of screen.)
2. Click on “Privacy and Security.”
3. In the “History” section, click on the “Clear History” button. (Alternatively, you can press CTRL+SHIFT+DEL on your keyboard to bypass steps 1-3.)
4. In the “Time Range to Clear” drop-down menu, choose “Everything.”
5. Make sure “Form & Search History” is checked.
6. Click Clear Now.