Your landlord most likely wants you to write a letter canceling your notice to terminate your rental agreement to protect the landlord. If you have been a good tenant and paid your rent timely, be assured the landlord does not want you to leave. Since you have served the landlord with a notice of termination, the landlord wants to document that you have canceled it.
You might consider the following:
Dear (name of landlord):
I hereby rescind my notice of termination of our lease dated (the date of your earlier notice) and withdraw same. This written communication shall serve to confirm my oral conversation with you rescinding my notice of termination.
That should do it. Make sure you keep a copy for your own files.