Can my apple iPhone block itself from a wifi provider?

Do you want to turn on Wi-Fi and then control which signal the phone connects with?

Check Settings ->Wi-Fi -> and scroll down and check your settings in these two categories:

1) Ask to Join Networks (you can chose Off, Notify, or Ask)

If you chose Off it will not connect to any _unknown_ network. You have to manually connect to one.

Notify and Ask are slightly more relaxed. "Known" networks are those you have set a password for in the past, so check those.

If I go somewhere where I use some other place's Wi-Fi, I go in after I'm finished and 'forget' the network, just in case.

2) Auto-Join Hotspot (you can chose Never, Ask to Join, or Automatic)

I cannot imagine why I would chose anything other than Never, unless I KNEW the person with the Hotspot.

Then I might turn it on if there was no Wi-Fi or Cellular option., and turn it back off when done. YMMV.

AFAIK, no model of the Apple iPhone can block what Wi-Fi network it can connect to. Most likely, it could be a setting on the wireless router/access point, that is preventing the phone from accessing it.

Your question isn't entirely clear, but I'd have to say no.

No. However, you can choose which Wi-Fi network to connect your iPhone to.