Can my employer read emails in my Gmail account?

Martin works for a large company that uses G Suite where the tech team can accesses employees' emails. Can he prevent this?

I work for a large company and use the Gmail set up for my account. As a senior manager, I have many confidential conversations internally and externally via email.

I have found out that one of the tech guys accesses employee's emails when requested to carry out checks by the CEO. Do they have the right to do this? I think it creates a feeling of mistrust and insecurity. Can I lock my account so only I can access it? Martin

Historically, the assumption has always been that companies own and can access mail used for company business. When I was a manager, I dictated letters to a secretary who typed them and filed copies. I never reached a level where these filing cabinets were locked and inaccessible, but they contained nothing of personal interest.