I have no idea how to disable it but it is free right now if you just call for at least a couple more months if you wanted to try it. Personally I wouldn't drive or ride without it, had it for last 16 years on all our vehicles but to each his own.
My last 3 years in speaking with Sirius rep when account is ready for renewal. "Sirius rep- your account is ready for renewal, as a valued customer, we can offer you a yearly subscription at $399 for the year." me-"Your satellites are orbiting the earth already, I'll offer you $59". Sirius rep-"Deal". Lol.
Not a huge fan of their channels, they seem to play older music even on newer stations. but I renew for a few reasons: Play be play sports since I live out of marked for the teams I grew up loving. Reception-I live in the NC mountains, radio is non existent, IPOD music gets old and streaming services are less reliable than radio do to lack of signal. I have yet to loose the sat signal while riding in the mountains. The only extremely painful issue is dealing with the Sirius outsourced call center.