If a school I attended was strictly online with no address is a address necessary? how could I move forward without this address information?

Yes, an address is necessary.

In order to be able to take an educational credit, it would need to be listed with the US Department of Education.

Even though you did not attend it, it would need to have a physical location for mail and business purposes.  That is the address you would use.  You can use Google to find your school or visit the schools' website to find their actual address.

If you are not reporting scholarship income or taking an education credit then you would not need to enter the school and could just go back and delete the education information for this school.