Uninstall HA Modules

I have some errors that are occurring (seemingly) from HA Integration: "Change HA Variable" node is outputting "Invalid access token or password".

In context of trying to deal with this I decided I don't need HA modules, thus would like to remove them. However, a few of them are in use., But I don't know how to find where they are used.

So my questions include:
How does one track down where nodes are "in use"? Can't find any info on this yet.
Once the uses are removed, can one use the Palette Manager to remove them? I can't see how but maybe this is because .....?

Much appreciated. I've been using NR for awhile but this is new territory. Usually adding modules, not removing them. But I'm trying to create clean install.

Hamburger at top right, select 'Search Flows' and then type the name of the node. Double clicking any of the results will highlight the node in the flow.

Yes, correct.
If they cannot be removed using the Palette manager, cd into your .node-red directory, and manually remove the node npm uninstall node-red-whatever-the-node-is