A lease obligates both you and your landlord for a set period of time, usually a year. Under a typical lease, a landlord can't raise the rent or change other terms, until the lease runs out (unless the lease itself provides for a change, such as a rent increase mid-lease).
Who Can Amend the Lease? When a landlord and tenant sign a lease agreement it forms a legally binding contract. The lease cannot be altered except through another written agreement signed by both parties unless the original lease specifically gives a party the power to change something on their own.
With Tenant Consent. If the tenant and landlord both agree to the change, the parties can either (1) execute a new lease or rental agreement that includes the new clause, or (2) amend the existing lease or rental agreement.
A change of terms would require the approval of both parties (landlord and tenant). Some leases do contain a clause allowing the landlord to change the terms, but these are usually not true leases. If your agreement has a similar clause than either party may change the terms by giving notice.
Once you have a clear idea of what you want and what your lease allows, you should communicate with your landlord in a respectful and professional manner. You should explain your situation and your reasons for renegotiating, and present your proposal in a way that shows how it can benefit both parties.
State laws on leases and rental agreements can vary, but a landlord or property management company should provide you with a copy of your signed lease upon request. You should make your request in writing, so you have proof if there is a dispute later.