Rogers Wireless in Canada has an offer with their family wireless plan, you get three spotify accounts free for two years.
I just signed up so me and the wife, and my daughter each get a spotify account free.
To answer the OP's question, on the MyRogers page where you selected spotify, you can select cancel this service,
then select another offer like Shomi, then cancel Shomi like you just did with spotify.
Now select spotify again, and all boxes next to your phone lines will be blank again.
I had the problem when I selected the first phone line on my account and linked it to my spotify account through my facebook login,
then when I went to link the second line on my account to another spotiy account through facebook,
the cookies/autolog logged me in again on same spotify account.
It took me forever with customer service figuring out how to clear those boxes so I hope this helps you.
My problem is now that I cancelled the premium like rogers told me to, beforeI linked the account,
it still says my premium is expiring in 30 days?