Q: how do i connect to internet with no phone service

i canceled phone service to my iphone 4 and now trying to erase all contents and settings but it comes up as unable to join network.  My network is fine as i am using it on my newer phone.  How do i get this phone to connect to wi-fi so it will erase my information.  I already removed phone from my icloud account but it still shows my apple i.d. in phone as well as my phone number.  How do i get this information out of there.