Domain Mapping issue in ZOHO Desk

Domain Mapping issue in ZOHO Desk

Dear All

    Our Domain is Controldesksolutions.com .We are trying to do domain mapping and its asking for add CNAME entry in DNS site . we have already add CNAME to our hosting site .  and add subdomain support.controldesksolutions.com 
but we want to map support.controldesksolutions.com CNAME to desk.cs.zohohosti.in . should I add another cname entry or delete www.controldesksolutions CNAME entry and add support.controldesksolutions.com