Go to the Spotify website, click on your profile picture in the top right corner and select “Log out of all devices”.
No, changing your Spotify password does not log everyone out.
Spotify offers a way to remove followers from your account. To do this, go to the Spotify website and log in to your account. Click on “Account” and then “Followers”. You will see a list of all the people who have followed you. Click on the person’s name and then click on “Remove” next to their name.