Most written leases provide for this. Since you don't have a written lease, your tenants are on month to month. You can give them a 30 day notice that you are changing lease terms and you want them to sign a new one year lease with you.
If the property is under rent control, I do not think that if they do not comply, that this will give you enough to evict them, but you can try. If they fail to give you a key, you can now point that out in the new lease that provides for that, and you can try to evict them for failure to sign a new month to month lease that now has that provision in it.
If their rent is really low, I doubt that they will try to fight you on this, so try it.
This is general legal advice intended for informational purposes only and does not create and attorney/client relationship. If you wish further advice, please contact an attorney of your own choosing or you may contact me for further advice and make other arrangements including retaining my services.