Correct spelling, explanation: originally, the word ignore comes from the Latin ignorare. But many words, including this one, came to function in English not straight from Latin, but through French. The French spelling of the word was ignorer. Keep in mind that the last r was silent, so when the word was borrowed, it was organically cut off and only the ending e was left, as it suits the pronunciation and fits well with other English words.

Definition of ignore:
verb
1. to purposefully not notice something
Due to societal expectations, we tend to ignore signs of depression in men; there should be something done about that.
My children completely ignore the mess in their rooms and then throw a tantrum when I ask them to clean it up.

Incorrect spelling, explanation: despite the fact that this spelling can reflect the pronunciation of the word ignore, ignor is not a correct word. While pronunciation is a factor in deciding the spelling, the most important thing is usually the origin of the word. In the case of ignore, the original word is ignorare which then influenced other borrowed forms. After years of adjustments, the e at the end is there to remind us of the original word and to guide the pronunciation.

Incorrect spelling