When resetting switches to factory default it's important to note that Vlan information from switches in any mode except transparent mode switches store their Vlan information in a vlan.dat file in their flash memory. If the switch is in VTP transparent mode then the Vlan configuration could also be stored in the running configuration as well as the start up configuration
Delete Vlan information commands
Remove the vlan.dat file (Only command required for a VTP server\client mode switch)
SW1 > enable
Clear startup\running config
Erasing the startup-config and reloading inherently removes the running config if the changes are not saved before reload.