SPOTIFY CONNECT DEVICE REMOVE

[badmoonproject]

Hello, i have a huge problem.
I am a professional hifi dealer, and on my spotify app is EVERY receiver & every spotify connect enabled speaker i have have sold in my shop, now when i go to my car it sometimes starts to play on one of the speakers from my customers, and that is not so funny for them. Please help me to remove all the devices from my account.
Log of from all devices, and also changing the password as described, doesnt solve the problem at all.
Every speaker still is in my list.