How Remove Spotify & Why on My Machine

[RhoXS]

I run a very lean and fast PC with mostly business associated programs and I am the only user as it located in my home office. All installed programs are carefully controlled and Spotify is certainly never anything that would have ever been intentionally installed, at least on this machine. A clean install was done about 5 weeks ago but, to my unpleasant surprise, during a routine check for unwanted start up items, two, "Disabled",  Spotify line items now appear in the Task manager Startup Tab. There is no Spotify line item in the Uninstall program dialog.

First - Please tell me how to fully delete the Spotify Software.

Second - how did it infect my machine? I understand Spotify is an accepted and popularly used streaming service but I never installed it, absolutely no one else has access to my machine as it uses a very secure password only in my head, and, as a result, finding it is very offensive and absolutely makes me mistrust this service.

Thank you.