Can one block all inbound calls to the toll free number? (trying to reduce spam charges)

I've been using Ringcentral for several years now, and have never used or given out the toll free number assigned to me by Ringcentral. I get a minimum of 10 spam calls to this number per week, and each one is a 5-6 cent charge. Is there any way to block all inbound calls to the Ringcentral-assigned toll free number? I am just as happy to delete the number, if that's the only option available. Thanks for any help you can give!