Hi Muz, there are two possible sources for that:

(1) Saved Login in Lockwise, Firefox's Password Manager

To check on that: "3-bar" menu button > Logins & Passwords

(2) Form history

If you arrow down to the unwanted suggestion and on the keyboard try the Delete key alone or Shift+Delete, does that remove it?

Unfortunately, Form history is an all-or-nothing feature. If you want to turn it off, you can do that on the Options page, custom History settings. More info: Control whether Firefox automatically fills in forms.

Both Lockwise and Form history are separate from the four categories of data that can appear in the main address bar drop-down, so there's no conflict there. I'm not sure if you meant something different when you said "web address bar search suggestions."

Thanks jscher2000, I went into " Control whether Firefox automatically fills in forms " and read about "Deleting individual form entries" it made me realise I hadn't before used the down arrow to highlight the entries I wanted to delete and once I did, I was able to delete those entries no problem. Cheers Muz