How to grant access to former employee Google Drive items

[alehal]

Hello

I am new to the process for this in Google admin console as my manager was one who used to grant this type of access. Unfortuenly he has left and did not provide any info on how to grant this access. So basically Head of our School advised she need access to his Google folder items which I believe his My Drive items. How do we grant this access for her inside of Google admin console