If I am doing all the work as manager does the owner have the right to split up money between me and the old manager?

It is difficult to answer your question because there are not enough facts to understand the relationship between you, the "old manager", and "new management".

Furthermore, it is not clear whether you are an employee or an independent contractor, or whether there is any written or oral agreement that covers the relationship between you and the owner.

You should retain an attorney who is familiar with commercial contracts to whom you can provide all of the facts and supporting evidence so s/he can help you determine your rights.

Disclaimer: This post does not constitute legal advice and does not establish an attorney-client relationship.