The basic requirement - 240.24(B) - is that each tenant must have access to the overcurrent devices that serve loads in their space. There is no rule about anyone else also having access to the same overcurrent devices. For my part, I would not want a tenant in my building to be able to turn off a breaker that serves a load in my space. But the NEC is silent on this issue.
This would not be a concern of yours, but there may be building code requirements that come into play. For example, there might be a requirement that there be a sufficient fire rating on the walls or floors that separate the two living units. You would not want a fire in the basement apartment to spread into the upper apartment, or to release smoke into the upper apartment. I only mention this because I have seen it discussed on one or more of the TV shows that deal with rennovating houses.