First off – this is a job for a licensed electrical contractor – with liability insurance.
Even if you are a qualified electrician – and judging by your question, probably not. Unless you own the building you are working on – you probably cannot legally make changes to a commercial building occupied by others. Laws vary by state, I’m in California, so those are the laws with which I’m most familiar.
Secondly if the ground and neutral bars are the same, then you may have a service box rather than a load distribution center. In most cases, the ground and neutral bars are only tied together at the service entrance and should be kept separate from that point on.
But that just re-inforces my point – get a licensed electrical contractor.