Boot with a live CD or in rescue mode (not even sure how to do that with grub 2) and disable wpa_supplicant.
Ah, here we are
It explains it pretty well. Once you're in the /mnt/sysimage, you can disable wpa_supplicant with
sytemctl disable wpa_supplicant.service
I would do
and disable other things you don't need on boot. For example, you may not want sendmail (which will also probably hang the system if it can't immediately connect to the network.) To disable anything, just use a command like the one I gave above, for example systemctl disable sendmail.service
I haven't used the rescue method myself--back in the old days, when Fedora booted, there was an option to hit I (upper case i, though I'm not sure if upper case was required) to be asked, one by one, if you wanted a service to start, but I don't think they have that anymore, which would have made situations like this much easier to handle, but that's progress.