If I just signed to buy a condo and am closing next month, however I just learned there is a tenant and a property management company involved, do I have to honor the contract with the management company?

When a home is sold, the buyer acquires it subject to any leases--the leases go with the home. You would not need to renew the lease after it expires, but if there is a written lease, you would be stuck with the tenant until the expiration...and possibly longer, inasmuch as if the tenant does not voluntarily leave at that time, you would have to bring an eviction action in court, which will take at least several weeks, to get the tenant out.

Failing to disclose the existence of a renter would be fraud, since this is a material (or critical) fact affecting whether one would choose to buy this property or not, and there is no credible way the seller would not have known of the tenant (i.e. this was a knowing or deliberate misrepresentation). Fraud would allow you to void, or undo, the contract--you get your deposit back (if you've paid any) and the deal is over. Alternately, you may be able sue get money compensation, such as money to pay for the cost of eviction and for you not being able to live in or otherwise use the condo for a number months.

There are a number of reasons why looking to void the contract and get out of the deal is likely the better option:

1) As a landlord-tenant attorney, my experience is that if you are unlucky enough to end up with a bad tenant, he or she can make the process of evicting him or her expensive and slow, and do a lot of damage to the property in the meantime. You don't know if you have a bad tenant--you don't know anything about the tenant. He or she could be a good tenant and good person, or could be the sort of nightmare tenant that lawyers tell stories about for years, or anything in between. Not knowing, you may not wish to take the chance that this will be one of the bad ones.

2) You don't know anything about the tenancy yet--e.g. what if it's for another year, not 6 months? What if the lease gives the tenant the right to renew? Etc. There are too many variables to be comfortable going into this situation.

3) A seller who woud lie about a tenant will lie about other things. There may be other significant problems of which you are unaware.