You can delete the entire list of Recent calls at once or selectively delete entries.
Open the Recent tab.
Tap the Menu icon (at the upper-right corner of the screen).
Tap Clear to select entries to remove from the list. Checkmark the entries to delete, tap Clear, then Yes.
Tap Clear all to remove all of the entries from the list. Tap Yes to confirm you want to Clear (at the bottom of the screen), the entire list.
You can also select a specific number to be deleted. Touch and hold an entry in the Recent list to open its Context menu. Tap Clear all logs of this number, then tap Yes to confirm.