How to build a supercell model with a vacancy?

Hi, everyone:
I want to build a supercell model with oxygen vacamcy using CASTEP to study the effects of varied oxygen vacancies and surface vacancy on the performances of (LaSr)(CoFe)O,but I don't know hou to build the models with vacancies. Could you do me a favor? Any hands will be appreciated.

Thanks in advance

Sincerely
Li