BlackBerry Curve Smartphone displays either missed calls or All Calls in the Message List. But if you want to clear the calls in the Message List then you can use BlackBerry 8520 options for changing the call logging types.
Press the menu button on BlackBerry 8520 Smartphone and select Options from the list.
In the Options screen, select Phone Options.
In the Phone Options screen, navigate to Call Logging
Under the Call Logging screen set the value for Show These Call Log Types in Message List to None.
This would clear all the calls from the Message List in BlackBerry Curve Smartphone.