I purchased a duplex that already has tenants residing in it under a lease from the previous owner. The lease expires in one year, but the rent being paid is extremely low for the area because the old owner was renovating the property. The old owner explained to me that he told the tenants the rents would be increased after the renovations were completed. When the renovations were completed, the old owner sold the property to me. The tenants leases don't expire until the end of next year. Can I legally void the old leases and have them sign a lease with me? Can I legally increase their rents when they sign a new lease with me to an amount more appropriate for that area?

I purchased a duplex that already has tenants residing in it under a lease from the previous owner. The lease expires in one year, but the rent being paid is extremely low for the area because the old owner was renovating the property. The old owner explained to me that he told the tenants the rents would be increased after the renovations were completed. When the renovations were completed, the old owner sold the property to me. The tenants leases don't expire until the end of next year. Can I legally void the old leases and have them sign a lease with me? Can I legally increase their rents when they sign a new lease with me to an amount more appropriate for that area?

No. You are stuck with the lease.

Not legal advice. See an attorney.

The tenants have tenants rights under the existing lease, so if they do not void the lease voluntarily, you need to abide by their existing lease until it expires. If you plan to increase rent or not renew, you need to give them notice in accordance with the terms of the existing lease.