You are trying to reprovision a switch in a different part of your network. However, you still see the old VLANs configured from the old network. How can you rectify the problem?

vlan.dat is the database for VLANs configured on a switch either manually or through VTP. It is persistent even if config.text (startup-configuration) is deleted. You must manually delete vlan.dat. Upgrading the IOS will not delete vlan.dat. Typing erase startup-config, confirming it, and reloading will not remove the current vlan.dat. Typing clear vlan will not remove the current vlan.dat.