Can i use muprucin ointment in my itching anus?

It can be used at that location. Whether or not it provides any benefit would depend on why there is itching. The ointment does have some barrier qualities aside from the antibacterial effect. Unless there is a bacterial infection at the site it is likely to do little.

If so prescribed, otherwise you are experimenting and mupirocin is not likely to help. Many times itching is self limited and resolved without intervention, see your doc if symptoms persist.