My old apple ID is being used for the iCloud account. I need to change it to my current Apple ID, My old apple ID is being used for the iCloud account. I need to change it to my current Apple ID

You will have to sign out from the iCloud preference pane and sign in with the new ID. Of course when you sign out all your iCloud data - email, calendars, contacts - will disappear from your Mac, assuming you have indeed been syncing them to the iCloud account you want to stop using. You can transfer the calendars and contacts manually, but you can't move the email addresses from one iCloud account to another.